To all:
The deadline for Part 1 of the project is over.
Some of you have sent your files in 07 format. Do give me some time to access as currently my laptop cant open them. need to use another computer to open that.
So dont worry about that.
Some of you have not followed my instructions. No acknowledgments, incorrect length of reflection. Some just copied wholesale from the website without understanding fully wat was being written. Some just took from the textbook which was really short. Marks would be deducted accordingly if so.
Late submissions from now onwards will result in loss of marks except for those who have approached me personally due to valid reasons. No submissions will cause a ZERO MARK to be awarded.
Note: some of your pics arent uploaded in the blog. But pls make use of them when you get together in your groups to design the poster. Thanks
A gentle reminder: This project will be counted as a CA mark in Term 3. No submission or late submission will result in YOU getting 0 marks in Term 3. TAKE NOTE!
Friday, June 20, 2008
Refraction of Light by 2E2 Chen Jing
!what do you learn about that particular topic?
I learn that the The bending of light that occurs when light passes from one transparent material to another is called refraction of light.light bends because its speed hanges as it moves from one transparent material to another.
light travels slower in more dense materials than in less dense materials.therefore light travels slower in glass than in air.
and i know many effects of refraction of light.such as we can use refraction of light to made the words appear to be nearer to the surface of the glass than they actually are.
From:textbook resource!
summarise the key points of that topic.
Refraction is the bending of light that takes place at a boundary between two materials having different indices of refraction.
Refraction is due to a change in the speed of light as it passes from one medium to another. The change in direction of the ray (represented by the heavy line in each diagram) is what is meant by the term refraction, which just means ¡°bending¡± or ¡°breaking.¡±
From:http://mintaka.sdsu.edu/GF/explain/optics/refr.html!
anything interesting to add?I
n 1621, a Dutch physicist named Willebrord Snell (1591-1626), derived the relationship between the different angles of light as it passes from one transperent medium to another.
When light passes from one transparent medium to another, it bends according to Snell's law which states:Ni * Sin(Ai) = Nr * Sin(Ar),
where:Ni is the refractive index of the medium the light is leaving,Ai is the incident angle between the light ray and the normal to the meduim to medium interface,Nr is the refractive index of the medium the light is entering,Ar is the refractive angle between the light ray and the normal to the meduim to medium interface.
From:http://www.ps.missouri.edu/rickspage/refract/refraction.html
I learn that the The bending of light that occurs when light passes from one transparent material to another is called refraction of light.light bends because its speed hanges as it moves from one transparent material to another.
light travels slower in more dense materials than in less dense materials.therefore light travels slower in glass than in air.
and i know many effects of refraction of light.such as we can use refraction of light to made the words appear to be nearer to the surface of the glass than they actually are.
From:textbook resource!
summarise the key points of that topic.
Refraction is the bending of light that takes place at a boundary between two materials having different indices of refraction.
Refraction is due to a change in the speed of light as it passes from one medium to another. The change in direction of the ray (represented by the heavy line in each diagram) is what is meant by the term refraction, which just means ¡°bending¡± or ¡°breaking.¡±
From:http://mintaka.sdsu.edu/GF/explain/optics/refr.html!
anything interesting to add?I
n 1621, a Dutch physicist named Willebrord Snell (1591-1626), derived the relationship between the different angles of light as it passes from one transperent medium to another.
When light passes from one transparent medium to another, it bends according to Snell's law which states:Ni * Sin(Ai) = Nr * Sin(Ar),
where:Ni is the refractive index of the medium the light is leaving,Ai is the incident angle between the light ray and the normal to the meduim to medium interface,Nr is the refractive index of the medium the light is entering,Ar is the refractive angle between the light ray and the normal to the meduim to medium interface.
From:http://www.ps.missouri.edu/rickspage/refract/refraction.html
Refraction of Light by 2E2 Tan Chew Mei
i.What is refraction of light ?
Refraction is the change in direction of a wave due to a change in its speed. This is most commonly seen when a wave passes from one medium to another. Refraction of light is the most commonly seen example, but any type of wave can refract when it interacts with a medium, for example when sound waves pass from one medium into another or when water waves move into water of a different depth. Refraction is also described by Snell’s Law.
ii.When does it happen? How will light bend ?
In optics, refraction occurs when light waves travel from a medium with a given refractive index to a medium with another. At the boundary between the media, the wave's phase velocity is altered, it changes direction, and its wave length increases or decreases but its frequency remains constant. For example, a light ray will refract as it enters and leaves glass; understanding of this concept led to the invention of lenses and the refracting telescope.
iii. What is refractive index ?
Refraction can be seen when looking into a bowl of water. Air has a refractive index of about 1.0003, and water has a refractive index of about 1.33.
Iv. Effect of refraction ?
refraction can make objects appear closer than they are, it is responsible for allowing water to magnify objects. First, as light is entering a drop of water, it slows down. If the water's surface is not flat, then the light will be bent into a new path. This round shape will bend the light outwards and as it spreads out, the image you see gets larger.
Refraction is the change in direction of a wave due to a change in its speed. This is most commonly seen when a wave passes from one medium to another. Refraction of light is the most commonly seen example, but any type of wave can refract when it interacts with a medium, for example when sound waves pass from one medium into another or when water waves move into water of a different depth. Refraction is also described by Snell’s Law.
ii.When does it happen? How will light bend ?
In optics, refraction occurs when light waves travel from a medium with a given refractive index to a medium with another. At the boundary between the media, the wave's phase velocity is altered, it changes direction, and its wave length increases or decreases but its frequency remains constant. For example, a light ray will refract as it enters and leaves glass; understanding of this concept led to the invention of lenses and the refracting telescope.
iii. What is refractive index ?
Refraction can be seen when looking into a bowl of water. Air has a refractive index of about 1.0003, and water has a refractive index of about 1.33.
Iv. Effect of refraction ?
refraction can make objects appear closer than they are, it is responsible for allowing water to magnify objects. First, as light is entering a drop of water, it slows down. If the water's surface is not flat, then the light will be bent into a new path. This round shape will bend the light outwards and as it spreads out, the image you see gets larger.
Refraction of Light by 2E1 The Su Zin
After doing research about this topic, I have learnt more concerning with the topic: refraction such as its laws and rules and also about refractive index.
1)Refraction
Refraction refers to the change in direction of light when it moves from one transparent medium into another transparent material which causes it to travel at a different speed.
Light slows down
Visible light is electromagnetic radiation or waveform. The speed or velocity of light in a vacuum is about 186,000 miles per second or 300,000 kilometres per second. The velocity of light or other electromagnetic radiation is typically slower when it passes through a transparent material. For example, the speed of light in water is about 140,000 mi/sec or 226,000 km/sec.
2)Refraction Rules When visible light passes through a transparent material such as glass and water, its velocity(speed) changes according to the index of refraction of the material. The index of refraction of air is about 1.00 and that of water is 1.33. When the beam of light enters water at an angle, it is bent or refracted as a result of the decrease in velocity.
Light is refracted inward when entering medium of higher index of refraction
Light is refracted outward when entering medium of lower index of refraction
The bending occurs because light travels more slowly in a denser medium.
Why does the light beam bend?
Considering a group of soldiers marching into a muddy field at an angle to their direction of travel can explain how a beam of light will be refracted. As the soldiers try to stay in a line, the direction of travel would bend because marching in mud would slow them down, starting with the first group to enter the field. Then, as they leave the muddy area, they go to their original speed, thus bending the direction of travel again. The original direction and the final direction are parallel but displaced.
The same thing happens when a beam of light enters a transparent material at an angle.
Example of how light is refracted when passes through different medium.
3 )INDEX OF REFRACTION
Refractive index is a number which indicates the power of refraction of a given medium relative to a previous medium. The absolute refractive index of a medium is the speed of light in a vacuum (air) divided by the speed of light in that medium.
Symbol is “n”. The larger the index ,the smaller the speed of light.
n = c/v
4)THE EFFECTS OF REFRACTION
Refraction has some unusual effects in everyday life.
-When a submerged object is viewed from above the surface of water, it appears closer to the surface than it is. This is due to light rays from the object being bent away from the normal as they pass out of the water (the more dense medium) into air (the less dense medium).
-The ratio of the real depth of the object to its apparent depth equals the refractive index of water.
Here are some examples of the EFFECTS:
eg1 - Apparent Depth in Water
In the above diagram, the chest seems to be nearer to the surface, but it is not. Refraction causes the chest to appear nearer to the surface than it actually is when it is in transparent material, water .
When you look at something under the water, not only the position of the object is not located at the place you though it was. The shape of the object is also changed. Location of the image and its shape are all depend on the location you view it.
eg2- In this diagram, the straw seems bent in the glass.
Refraction causes point X to appear nearer to the surface at Y so we see that that the straw appears to bend nearer to the surface of the water. This is one of the effect of refraction.
Eg.3 Pencil in water glass
You can also see this effect by putting a pencil in a glass of water. It appears as if the pencil is broken, but it is just because of the refraction of light.
The light from the pencil is refracted as it passes from the water to the glass to air, causing it to be displaced. Since the surface of the glass is curved, the water in the glass also acts as a magnifying glass, slightly enlarging the pencil.
So here is the link for mini short quiz, very simple quiz. =)
http://www.school-for-champions.com/science/light_refraction.htm#Mini-quiz
Acknowledgement
1 . http://sol.sci.uop.edu/~jfalward/refraction/refraction.html
2.http://sg.answers.yahoo.com/question/index;_ylt=ApfjYqHaykzhEnCDtDjBpjYh4wt.;_ylv=3?qid=20070902013243AA3gdvF
3. http://www.school-for-champions.com/science/light_refraction.htm
http://www.phy.ntnu.edu.tw/ntnujava/
4. The Usborne Illustrated Dictionary Of Physics
1)Refraction
Refraction refers to the change in direction of light when it moves from one transparent medium into another transparent material which causes it to travel at a different speed.
Light slows down
Visible light is electromagnetic radiation or waveform. The speed or velocity of light in a vacuum is about 186,000 miles per second or 300,000 kilometres per second. The velocity of light or other electromagnetic radiation is typically slower when it passes through a transparent material. For example, the speed of light in water is about 140,000 mi/sec or 226,000 km/sec.
2)Refraction Rules When visible light passes through a transparent material such as glass and water, its velocity(speed) changes according to the index of refraction of the material. The index of refraction of air is about 1.00 and that of water is 1.33. When the beam of light enters water at an angle, it is bent or refracted as a result of the decrease in velocity.
Light is refracted inward when entering medium of higher index of refraction
Light is refracted outward when entering medium of lower index of refraction
The bending occurs because light travels more slowly in a denser medium.
Why does the light beam bend?
Considering a group of soldiers marching into a muddy field at an angle to their direction of travel can explain how a beam of light will be refracted. As the soldiers try to stay in a line, the direction of travel would bend because marching in mud would slow them down, starting with the first group to enter the field. Then, as they leave the muddy area, they go to their original speed, thus bending the direction of travel again. The original direction and the final direction are parallel but displaced.
The same thing happens when a beam of light enters a transparent material at an angle.
Example of how light is refracted when passes through different medium.
3 )INDEX OF REFRACTION
Refractive index is a number which indicates the power of refraction of a given medium relative to a previous medium. The absolute refractive index of a medium is the speed of light in a vacuum (air) divided by the speed of light in that medium.
Symbol is “n”. The larger the index ,the smaller the speed of light.
n = c/v
4)THE EFFECTS OF REFRACTION
Refraction has some unusual effects in everyday life.
-When a submerged object is viewed from above the surface of water, it appears closer to the surface than it is. This is due to light rays from the object being bent away from the normal as they pass out of the water (the more dense medium) into air (the less dense medium).
-The ratio of the real depth of the object to its apparent depth equals the refractive index of water.
Here are some examples of the EFFECTS:
eg1 - Apparent Depth in Water
In the above diagram, the chest seems to be nearer to the surface, but it is not. Refraction causes the chest to appear nearer to the surface than it actually is when it is in transparent material, water .
When you look at something under the water, not only the position of the object is not located at the place you though it was. The shape of the object is also changed. Location of the image and its shape are all depend on the location you view it.
eg2- In this diagram, the straw seems bent in the glass.
Refraction causes point X to appear nearer to the surface at Y so we see that that the straw appears to bend nearer to the surface of the water. This is one of the effect of refraction.
Eg.3 Pencil in water glass
You can also see this effect by putting a pencil in a glass of water. It appears as if the pencil is broken, but it is just because of the refraction of light.
The light from the pencil is refracted as it passes from the water to the glass to air, causing it to be displaced. Since the surface of the glass is curved, the water in the glass also acts as a magnifying glass, slightly enlarging the pencil.
So here is the link for mini short quiz, very simple quiz. =)
http://www.school-for-champions.com/science/light_refraction.htm#Mini-quiz
Acknowledgement
1 . http://sol.sci.uop.edu/~jfalward/refraction/refraction.html
2.http://sg.answers.yahoo.com/question/index;_ylt=ApfjYqHaykzhEnCDtDjBpjYh4wt.;_ylv=3?qid=20070902013243AA3gdvF
3. http://www.school-for-champions.com/science/light_refraction.htm
http://www.phy.ntnu.edu.tw/ntnujava/
4. The Usborne Illustrated Dictionary Of Physics
Colours of Light by 2E1 Jason
Colour:
Colour is the visual perceptual property corresponding in humans to the categories called red, yellow, blue, black, etc. Colour derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors.
White light is a mixture of different colours and when it passes through a glass prism, the light splits up into the colours you see in a rainbow. Spectrum, (white light) consists of Red, Orange, Yellow, Green, Blue, Indigo and Violet. The separation of splitting of white light into its separate colours is known as ‘Dispersion’. The colours of the spectrum can be recombined by using a second prism or spinning a colour wheel, we can get white light.
Mixing Coloured Lights
The primary colours of light are red, blue, and green. You can get white light or any other colour by mixing just three colours. If you mix two primary colours at a time, you will get magenta, yellow, and cyan.
Colour Filters
Colour filter is the clear plastic or glass which only lets through some of the colours meanwhile the other colours is being absorbed.
When white light (spectrum) shines on a coloured object, some of the colours in the spectrum are reflected and some are being absorbed. We can see the colour that is reflected light.
Credits:
http://en.wikipedia.org/wiki/Colour
http://wolfstone.halloweenhost.com/Lighting/colmix_ColorMixing.html
Explore Your World with SCIENCE DISCOVERY 2 [Chapter 8.4, colour]
Colour is the visual perceptual property corresponding in humans to the categories called red, yellow, blue, black, etc. Colour derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors.
White light is a mixture of different colours and when it passes through a glass prism, the light splits up into the colours you see in a rainbow. Spectrum, (white light) consists of Red, Orange, Yellow, Green, Blue, Indigo and Violet. The separation of splitting of white light into its separate colours is known as ‘Dispersion’. The colours of the spectrum can be recombined by using a second prism or spinning a colour wheel, we can get white light.
Mixing Coloured Lights
The primary colours of light are red, blue, and green. You can get white light or any other colour by mixing just three colours. If you mix two primary colours at a time, you will get magenta, yellow, and cyan.
Colour Filters
Colour filter is the clear plastic or glass which only lets through some of the colours meanwhile the other colours is being absorbed.
When white light (spectrum) shines on a coloured object, some of the colours in the spectrum are reflected and some are being absorbed. We can see the colour that is reflected light.
Credits:
http://en.wikipedia.org/wiki/Colour
http://wolfstone.halloweenhost.com/Lighting/colmix_ColorMixing.html
Explore Your World with SCIENCE DISCOVERY 2 [Chapter 8.4, colour]
Colours of Light by 2E4 Jeremy Lim
In this topic I have learn about how colours are produce , what is dispersion of light and to recombine colours back after spitting them and also what is the effect of mixing colours as well as what is primary colours.
White light which is also known as ordinary light actually is a mixture of different colours. And when that white light pass through a glass prism the light actually spits up into 7 different colours and that process is call dispersion.
The spectrum consist of 7 beautiful colours, they are red, orange, yellow, green, blue, indigo, violet. It is also difficult to say when one colours ends or start as these colours merge into one another gradually.
The reason why there is always (maybe) a rainbow after a shower of rain is because the raindrops act like small prism and when sunlight passes through them …. They form the colours of the spectrum.
And since we are able to separate those seven colours from the spectrum, thus we are also able to rejoin the seven colours back into white light. And in order to do that is 2 ways.
The first way is to add in another prism or to spin a colour wheel and another
name for the colour wheel is call a Newton disc.
Lights of different colours can be mixed together to produce other colours and in fact white light and light of other colours can be obtained by mixing 3 colours, these colours are red, blue , green. These colours are called primary colours.
Here are the *formula* of colours, red + blue = magenta, red+ green = yellow, blue + green = cyan. And by adding the 3 primary we get white colours.
Clear plastic or glass only let through some colours and the other colours are absorbed are call colour filter. When white light shines on a coloured object, some colour are reflected and some are absorbed.
To end my project work, I want to say that the colour of an object is the colour of the light that is reflected from it into our eyes. And if no light is reflected the object would be black. Black is not a colour it is just something that indicates the absence of light.
Text book resource*
White light which is also known as ordinary light actually is a mixture of different colours. And when that white light pass through a glass prism the light actually spits up into 7 different colours and that process is call dispersion.
The spectrum consist of 7 beautiful colours, they are red, orange, yellow, green, blue, indigo, violet. It is also difficult to say when one colours ends or start as these colours merge into one another gradually.
The reason why there is always (maybe) a rainbow after a shower of rain is because the raindrops act like small prism and when sunlight passes through them …. They form the colours of the spectrum.
And since we are able to separate those seven colours from the spectrum, thus we are also able to rejoin the seven colours back into white light. And in order to do that is 2 ways.
The first way is to add in another prism or to spin a colour wheel and another
name for the colour wheel is call a Newton disc.
Lights of different colours can be mixed together to produce other colours and in fact white light and light of other colours can be obtained by mixing 3 colours, these colours are red, blue , green. These colours are called primary colours.
Here are the *formula* of colours, red + blue = magenta, red+ green = yellow, blue + green = cyan. And by adding the 3 primary we get white colours.
Clear plastic or glass only let through some colours and the other colours are absorbed are call colour filter. When white light shines on a coloured object, some colour are reflected and some are absorbed.
To end my project work, I want to say that the colour of an object is the colour of the light that is reflected from it into our eyes. And if no light is reflected the object would be black. Black is not a colour it is just something that indicates the absence of light.
Text book resource*
Refraction of Light by 2E1 Shahir
For thousands of years, people have noticed that a straight stick placed obliquely in water appears to be broken at an angle where it enters the water. This is the origin of the term "refraction," which means literally "broken back."
Refraction is the change of light that changes direction when it passes from one medium to another.
refraction occurs when light waves travel from a medium with a given refractive index to a medium with another.
At the boundary between the media, the wave's phase velocity is altered, it changes direction, and its wavelength increases or decreases but its frequency remains constant.
For example, a light ray will refract as it enters and leaves glass.the understanding of this concept led to the invention of lenses and the refracting telescope
from a less dense material to a denser material, light will slows down and refracted towards the normal, while from denser material into a less dense material, light speeds up and is refracted away from the normal.
The refractive index of a transparent optical medium, also called the index of refraction, is the factor by which the phase velocity is decreased relative to the velocity of light in vacuum, assuming linear propagation
effects of refraction are : -it causes an object to be nearer than it actually is when a transparent material is on top - a stick will appear to be bent inside a bearker filled with water.
From this topic, i have learned that refraction happens in our everyday life. It causes effects that are very unusual and refraction is an interesting topic to learn.
key points : -refraction happens when light changes direction when it passes from one medium to another -it causes effects that are unusual.
Refraction is the change of light that changes direction when it passes from one medium to another.
refraction occurs when light waves travel from a medium with a given refractive index to a medium with another.
At the boundary between the media, the wave's phase velocity is altered, it changes direction, and its wavelength increases or decreases but its frequency remains constant.
For example, a light ray will refract as it enters and leaves glass.the understanding of this concept led to the invention of lenses and the refracting telescope
from a less dense material to a denser material, light will slows down and refracted towards the normal, while from denser material into a less dense material, light speeds up and is refracted away from the normal.
The refractive index of a transparent optical medium, also called the index of refraction, is the factor by which the phase velocity is decreased relative to the velocity of light in vacuum, assuming linear propagation
effects of refraction are : -it causes an object to be nearer than it actually is when a transparent material is on top - a stick will appear to be bent inside a bearker filled with water.
From this topic, i have learned that refraction happens in our everyday life. It causes effects that are very unusual and refraction is an interesting topic to learn.
key points : -refraction happens when light changes direction when it passes from one medium to another -it causes effects that are unusual.
Reflection of light by 2E3 Huang Yue
What is reflection ???????
The bouncing of light off a mirror surface is called reflection.
Types of reflection?????
There are two types of reflection --regular reflection , diffuse reflection.
--When a parallel beam of light hits a smooth surface,it would be reflected as a parallel beam .This is called regular reflection.
--When a beam of light hits a rough surface,the individual rays are reflectedin different directions,then no image formed .This types of reflection is called diffuse reflection.
Uses of reflection of light,examples?
Uses of plane mirrors -----
—— the rear of a view mirror of a car can helps to see traffic behind the car.
——plane mirrors on walls makes a room brighter.
——people use plane mirrors to check their appearance.
Uses of curved mirrors----
——security mirrors are used in shops.
——blind corner mirrors helped driver to see objects around the corner.
——a concave mirror is used to reflect light into microscope.
Acknowledgements:
----Explore your world with science discovery 2
-----http://images.google.cn/imgres?imgurl=http://id.mind.net/~zona/mstm/physics/light/rayOptics/reflection/r1.jpg&imgrefurl=http://id.mind.net/~zona/mstm/physics/light/rayOptics/reflection/reflection1.html&h=300&w=400&sz=14&hl=zh-CN&start=17&um=1&tbnid=vcnBWStV9c6jCM:&tbnh=93&tbnw=124&prev=/images%3Fq%3Dreflection%2Bof%2Blight%26um%3D1%26complete%3D1%26hl%3Dzh-CN%26rlz%3D1T4XNLA_zh-CNSG277SG277%26sa%3DX
The bouncing of light off a mirror surface is called reflection.
Types of reflection?????
There are two types of reflection --regular reflection , diffuse reflection.
--When a parallel beam of light hits a smooth surface,it would be reflected as a parallel beam .This is called regular reflection.
--When a beam of light hits a rough surface,the individual rays are reflectedin different directions,then no image formed .This types of reflection is called diffuse reflection.
Uses of reflection of light,examples?
Uses of plane mirrors -----
—— the rear of a view mirror of a car can helps to see traffic behind the car.
——plane mirrors on walls makes a room brighter.
——people use plane mirrors to check their appearance.
Uses of curved mirrors----
——security mirrors are used in shops.
——blind corner mirrors helped driver to see objects around the corner.
——a concave mirror is used to reflect light into microscope.
Acknowledgements:
----Explore your world with science discovery 2
-----http://images.google.cn/imgres?imgurl=http://id.mind.net/~zona/mstm/physics/light/rayOptics/reflection/r1.jpg&imgrefurl=http://id.mind.net/~zona/mstm/physics/light/rayOptics/reflection/reflection1.html&h=300&w=400&sz=14&hl=zh-CN&start=17&um=1&tbnid=vcnBWStV9c6jCM:&tbnh=93&tbnw=124&prev=/images%3Fq%3Dreflection%2Bof%2Blight%26um%3D1%26complete%3D1%26hl%3Dzh-CN%26rlz%3D1T4XNLA_zh-CNSG277SG277%26sa%3DX
Colours of Light by 2E4 Jun Min Jung
How are colours being produced?
Colours are produced because of sun light(white light).
What is Dispersion of light?
The speed of light is slower in various than it is in a vacuum or outer space. When the light passes into a material at an angle, the light beam is bent or refracted according to Snell’s Law and the index of retraction of the material. But also, the speed of light through a material varies slightly with the wavelength or frequency of the light. Thus, each wavelength is refracted at a slightly different angle when passing through a material at an angle. This spreading out of the beam of light is called dispersion. This can be seen when sunlight passes through a glass prism.
How to get rainbow colours and to recombine colours again?
Rainbow is formed when sunlight (white light) passes through raindrops. Tiny droplets of water refract the white light from the sun and create a spectrum of colours similar to what happen in a prism. Since the droplets are spheres, the light is reflected internally in the droplets and the rainbow returns toward the direction of the light.
Since white light consists of seven colours, we should be able to get white light again by combining the colours together. There are two ways to recombine the colours.
• By using a second prism: When another prism is placed, the colours recombine.
• Spinning a colour wheel (also called a Newton’s disc\): When the wheel is turned quickly, the colours appear to mix and the wheel looks white.
What is primary colours?
Light of different colours can be mixed together to produce other colours. In fact, white light and other light of colours – red, blue and green. These three colours are called the primary colours.
Effects of Mixing of Colours
Mixing the primary colours two at a time gives the following colours:
• red + blue = green
• red + green = yellow
• blue + green = cyan
Mixing all three primary colours gives white light. That is:
• red + blue + green = white
http://www.school-for-champions.com/science/light_dispersion.htm
Textbook - p.128~p.130
Colours are produced because of sun light(white light).
What is Dispersion of light?
The speed of light is slower in various than it is in a vacuum or outer space. When the light passes into a material at an angle, the light beam is bent or refracted according to Snell’s Law and the index of retraction of the material. But also, the speed of light through a material varies slightly with the wavelength or frequency of the light. Thus, each wavelength is refracted at a slightly different angle when passing through a material at an angle. This spreading out of the beam of light is called dispersion. This can be seen when sunlight passes through a glass prism.
How to get rainbow colours and to recombine colours again?
Rainbow is formed when sunlight (white light) passes through raindrops. Tiny droplets of water refract the white light from the sun and create a spectrum of colours similar to what happen in a prism. Since the droplets are spheres, the light is reflected internally in the droplets and the rainbow returns toward the direction of the light.
Since white light consists of seven colours, we should be able to get white light again by combining the colours together. There are two ways to recombine the colours.
• By using a second prism: When another prism is placed, the colours recombine.
• Spinning a colour wheel (also called a Newton’s disc\): When the wheel is turned quickly, the colours appear to mix and the wheel looks white.
What is primary colours?
Light of different colours can be mixed together to produce other colours. In fact, white light and other light of colours – red, blue and green. These three colours are called the primary colours.
Effects of Mixing of Colours
Mixing the primary colours two at a time gives the following colours:
• red + blue = green
• red + green = yellow
• blue + green = cyan
Mixing all three primary colours gives white light. That is:
• red + blue + green = white
http://www.school-for-champions.com/science/light_dispersion.htm
Textbook - p.128~p.130
Colours of Light by 2E1 Vaishnavi
In this essay I am going to explain about our physics project. My topic was colours. From the project we have understood many things about colours.
Colour is simply light of different wavelengths and frequencies and light is just one form of energy that we can actually see.
The three primary colours are red, green and blue. Colour comes from light.
To see the colour physically we need to have a prism. When light from the sun passes through a prism, the light is split into the seven visible colours by refraction.
Refraction is caused by the change in speed experienced by a wave of light when it changes medium. The amount of energy in a given light wave is proportionally related to its frequency, thus a high frequency light wave has a higher energy than that of a low frequency.
Each colour has its own particular wavelength and frequency. Each colour can be measured in units of cycles or waves per second. The frequency of a wave is determined by the number of complete waves, or wavelengths, that pass a given point each second.
Higher frequency colours are - violet - indigo - blue lower frequency colours are - yellow - orange - red.
A high frequency light wave has a higher energy than that of a low frequency light wave.
Refraction of Light by 2E1 Fatima
What is refraction?
Refraction is the bending of a light when it passes from one transparent medium into another.
When and how does it happen?
Light changes direction because light travels at different speeds in different substances, causing it to be bent when it changes from one substance to another.
The degree of refraction depends in part on the angle at which the light hits the surface of a material. A line perpendicular to that surface is called the normal. The angle between the incoming light ray and the normal to the surface is called the angle of incidence. The angle between the refracted ray and the normal is called the angle of refraction. The angle of refraction cannot exceed 90°.
A ray of light refracts or deviates from its original path as it passes from one optical medium to another because the speed of light changes.
Refractive Index?
The amount of refraction can be found using the refractive index.
The speed at which light travels may change as it passes from one medium to another. Different substances will cause different changes to the speed of light. For example, glass slows light more than water.
To find the effect of a substance we can calculate its refractive index. This is a ratio of the speed of light in air or vacuum and the speed of light in the substance.
refractive index = speed of light in air/speed of light in substance
For example, the speed of light in air is 300,000 km/s and in glass it travels at about 200,000 km/s. Its refractive index is therefore 1.5. Water, however, has a refractive index of 1.33. This means that light rays are refracted more when they enter glass than when they enter water.
Effects of Refraction?
The effects of refraction:
1. Make things appear to be nearer
2. make objects in water appear to be bent
the pencil appears to be bent because of refraction
DK Reference Encyclopedia
http://www.tutorvista.com/content/physics/physics-ii/light-refraction/refraction-light.php
http://images.google.com.sg/
Refraction is the bending of a light when it passes from one transparent medium into another.
When and how does it happen?
Light changes direction because light travels at different speeds in different substances, causing it to be bent when it changes from one substance to another.
The degree of refraction depends in part on the angle at which the light hits the surface of a material. A line perpendicular to that surface is called the normal. The angle between the incoming light ray and the normal to the surface is called the angle of incidence. The angle between the refracted ray and the normal is called the angle of refraction. The angle of refraction cannot exceed 90°.
A ray of light refracts or deviates from its original path as it passes from one optical medium to another because the speed of light changes.
Refractive Index?
The amount of refraction can be found using the refractive index.
The speed at which light travels may change as it passes from one medium to another. Different substances will cause different changes to the speed of light. For example, glass slows light more than water.
To find the effect of a substance we can calculate its refractive index. This is a ratio of the speed of light in air or vacuum and the speed of light in the substance.
refractive index = speed of light in air/speed of light in substance
For example, the speed of light in air is 300,000 km/s and in glass it travels at about 200,000 km/s. Its refractive index is therefore 1.5. Water, however, has a refractive index of 1.33. This means that light rays are refracted more when they enter glass than when they enter water.
Effects of Refraction?
The effects of refraction:
1. Make things appear to be nearer
2. make objects in water appear to be bent
the pencil appears to be bent because of refraction
DK Reference Encyclopedia
http://www.tutorvista.com/content/physics/physics-ii/light-refraction/refraction-light.php
http://images.google.com.sg/
Electricity by 2E1 Darren Tan
What is electricity?
Electricity is a form of energy. Electricity is the flow of electrons. All matter is made up of atoms, and an atom has a center, called a nucleus. The nucleus contains positively charged particles called protons and uncharged particles called neutrons. The nucleus of an atom is surrounded by negatively charged particles called electrons. The negative charge of an electron is equal to the positive charge of a proton, and the number of electrons in an atom is usually equal to the number of protons.
How is electricity produce?
An electric generator is a device for converting mechanical energy into electrical energy. The process is based on the relationship between magnetism and electricity. When a wire or any other electrically conductive material moves across a magnetic field, an electric current occurs in the wire. The large generators used by the electric utility industry have a stationary conductor. A magnet attached to the end of a rotating shaft is positioned inside a stationary conducting ring that is wrapped with a long, continuous piece of wire. When the magnet rotates, it induces a small electric current in each section of wire as it passes. This current is what is used for electric power.
How are electricity used?
Electricity are used in many thing including computer that we used, oven that we use to warm up food, light that help us to see better, hand phone that let us contact other ETC.
Electricity is a form of energy. Electricity is the flow of electrons. All matter is made up of atoms, and an atom has a center, called a nucleus. The nucleus contains positively charged particles called protons and uncharged particles called neutrons. The nucleus of an atom is surrounded by negatively charged particles called electrons. The negative charge of an electron is equal to the positive charge of a proton, and the number of electrons in an atom is usually equal to the number of protons.
How is electricity produce?
An electric generator is a device for converting mechanical energy into electrical energy. The process is based on the relationship between magnetism and electricity. When a wire or any other electrically conductive material moves across a magnetic field, an electric current occurs in the wire. The large generators used by the electric utility industry have a stationary conductor. A magnet attached to the end of a rotating shaft is positioned inside a stationary conducting ring that is wrapped with a long, continuous piece of wire. When the magnet rotates, it induces a small electric current in each section of wire as it passes. This current is what is used for electric power.
How are electricity used?
Electricity are used in many thing including computer that we used, oven that we use to warm up food, light that help us to see better, hand phone that let us contact other ETC.
Refraction of Light by 2E1 Emily
REFRACTION.
If you have ever half submerged a straight stick into water, you have probably noticed that the stick appears bent at the point it enters the water.This optical effect is due to refraction.
Refraction is the change in direction of a wave due to a change in its speed.
Refraction happens when light passes from one medium to another.
When light passes from one medium to another, light from less dense media to a denser media will slow down and it is refracted towards the normal. But when light passes from denser media to less dense media, it will speeds up and it is refracted from the normal.
REFRACTIVE INDEX
The refractive index of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium.
EFFECTS OF REFRACTION
refraction has some unusual effects in everyday life. some examples are :
- when you place a glass block on top of your textbook, and observe. The words will appear to be nearer to the surface of the glass than they actually are.
- the object appears to be at a higher position than it actually is. for this reason, a swimming pool appears shallower than it really is.
- a pencil inside a beaker filled with water will appear to be bent.
From all the information i have gained, i have learnt that refraction occurs in everyday life. It is very interesting to know how it happens and what are the unusual effects caused by refraction.
The Key point of this topic is : Refraction happens when light changes direction when it passes from one transparent material into another. Refraction will cause an object appears to be at higher position than it actually is.
Science Textbook Chapter 8, Refraction. http://www.ps.missouri.edu/rickspage/refract/refraction.html http://en.wikipedia.org/wiki/Refraction
If you have ever half submerged a straight stick into water, you have probably noticed that the stick appears bent at the point it enters the water.This optical effect is due to refraction.
Refraction is the change in direction of a wave due to a change in its speed.
Refraction happens when light passes from one medium to another.
When light passes from one medium to another, light from less dense media to a denser media will slow down and it is refracted towards the normal. But when light passes from denser media to less dense media, it will speeds up and it is refracted from the normal.
REFRACTIVE INDEX
The refractive index of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium.
EFFECTS OF REFRACTION
refraction has some unusual effects in everyday life. some examples are :
- when you place a glass block on top of your textbook, and observe. The words will appear to be nearer to the surface of the glass than they actually are.
- the object appears to be at a higher position than it actually is. for this reason, a swimming pool appears shallower than it really is.
- a pencil inside a beaker filled with water will appear to be bent.
From all the information i have gained, i have learnt that refraction occurs in everyday life. It is very interesting to know how it happens and what are the unusual effects caused by refraction.
The Key point of this topic is : Refraction happens when light changes direction when it passes from one transparent material into another. Refraction will cause an object appears to be at higher position than it actually is.
Science Textbook Chapter 8, Refraction. http://www.ps.missouri.edu/rickspage/refract/refraction.html http://en.wikipedia.org/wiki/Refraction
Reflection of Light by 2E2 Zin Win
Reflection on a mirror surface.
I have learnt that reflection is the bouncing off light after hitting a mirror surfaces.
There are two type of reflection the 1st one is regular reflection and 2nd is the diffused reflection. Regular reflection is made out of a parallel beam of light which bounce off a smooth surface and an image is form while the diffuse reflection reflects on a rough surface the ray is reflected in different direction and no image is form.
The angle of incidence is equal to the angles of reflection in the plane mirror
Properties of plane mirror:
Virtual
Upright
Same size as the object
Laterally inverted
Uses of plane mirror :
helps a driver see the traffic behind ,
help a person check appearance
make a room bigger
periscope are made of two plane mirrors to see over obstacles
Convex mirrors from upright image that is always smaller than the object. They allow many things to be seen
Concave mirrors formed upright magnified images if the object is close to the mirror. If the image is further away, the image is inverted
I have learnt that reflection is the bouncing off light after hitting a mirror surfaces.
There are two type of reflection the 1st one is regular reflection and 2nd is the diffused reflection. Regular reflection is made out of a parallel beam of light which bounce off a smooth surface and an image is form while the diffuse reflection reflects on a rough surface the ray is reflected in different direction and no image is form.
The angle of incidence is equal to the angles of reflection in the plane mirror
Properties of plane mirror:
Virtual
Upright
Same size as the object
Laterally inverted
Uses of plane mirror :
helps a driver see the traffic behind ,
help a person check appearance
make a room bigger
periscope are made of two plane mirrors to see over obstacles
Convex mirrors from upright image that is always smaller than the object. They allow many things to be seen
Concave mirrors formed upright magnified images if the object is close to the mirror. If the image is further away, the image is inverted
Electricity by 2E4 Chanchai Kovitpornsin
Name class 2E4 index no. 18
Electricity
I have learnt electricity is a form of energy. It is very convenient because it be changed to other forms of energy.
How electricity produced
I have learnt electricity energy comes from 2 main sources. There are electricity and electricity cells.
Main electricity is generated in power station. The plugs of electricity appliances are inserted into mains sockets to obtain this electricity. Main electricity supplies a lot of energy.
Electricity cells give out only a little energy. They are used in many portable electrical devices and safe to use.
Electric Circuits
I have learnt to make an electrical appliance work, electricity must flow through it. The flow of electricity is called an electric current. An electric current flow only when there is: 1. A source of electrical energy and 2. A closed circuit.
Electric Current
I have learnt an electric current is the flow of electrons in one direction in a circuit.
Measuring Electric Current
I have learnt to measure the electric current, we use an ammeter.
The SI unit for electric current is the ampere (A). Smaller currents can be measured in milliamperes (mA)
1 A = 1000 mA
1 mA= 1/1000 A (or 0.001 A)
Voltage
I have learnt voltage is a measure of how much energy the electrons receive. To measure voltage we use a voltmeter.
The SI for voltage is the volt (V).
Used of electricity
Electrical energy is changed to sound energy in radios.
Electrical energy is changed to heat energy in rice cookers.
Electrical energy is changed to kinetic energy in electric fans.
Key points
Electricity is a form of energy.
Electricity energy comes from 2 main sources. There are electricity and electricity cells.
The flow of electricity is called an electric current. An electric current flow only when there is: 1. A source of electrical energy and 2. A closed circuit.
An electric current is the flow of electrons in one direction in a circuit
Voltage is a measure of how much energy the electrons receive. To measure voltage we use a voltmeter.
History
That certain objects such as rods of amber could be rubbed with cat's fur and attract light objects like feathers was known to ancient cultures around the Mediterranean. Thales of Miletos conducted a series of experiments into static electricity around 600 BC, from which he believed that friction rendered amber magnetic, in contrast to minerals such as magnetite, which needed no rubbing. Thales was incorrect in believing the attraction was due to a magnetic effect, but later science would prove a link between magnetism and electricity.
Information
http://en.wikipedia.org/wiki/Electricity
Science Discovery 2 textbook
Electricity
I have learnt electricity is a form of energy. It is very convenient because it be changed to other forms of energy.
How electricity produced
I have learnt electricity energy comes from 2 main sources. There are electricity and electricity cells.
Main electricity is generated in power station. The plugs of electricity appliances are inserted into mains sockets to obtain this electricity. Main electricity supplies a lot of energy.
Electricity cells give out only a little energy. They are used in many portable electrical devices and safe to use.
Electric Circuits
I have learnt to make an electrical appliance work, electricity must flow through it. The flow of electricity is called an electric current. An electric current flow only when there is: 1. A source of electrical energy and 2. A closed circuit.
Electric Current
I have learnt an electric current is the flow of electrons in one direction in a circuit.
Measuring Electric Current
I have learnt to measure the electric current, we use an ammeter.
The SI unit for electric current is the ampere (A). Smaller currents can be measured in milliamperes (mA)
1 A = 1000 mA
1 mA= 1/1000 A (or 0.001 A)
Voltage
I have learnt voltage is a measure of how much energy the electrons receive. To measure voltage we use a voltmeter.
The SI for voltage is the volt (V).
Used of electricity
Electrical energy is changed to sound energy in radios.
Electrical energy is changed to heat energy in rice cookers.
Electrical energy is changed to kinetic energy in electric fans.
Key points
Electricity is a form of energy.
Electricity energy comes from 2 main sources. There are electricity and electricity cells.
The flow of electricity is called an electric current. An electric current flow only when there is: 1. A source of electrical energy and 2. A closed circuit.
An electric current is the flow of electrons in one direction in a circuit
Voltage is a measure of how much energy the electrons receive. To measure voltage we use a voltmeter.
History
That certain objects such as rods of amber could be rubbed with cat's fur and attract light objects like feathers was known to ancient cultures around the Mediterranean. Thales of Miletos conducted a series of experiments into static electricity around 600 BC, from which he believed that friction rendered amber magnetic, in contrast to minerals such as magnetite, which needed no rubbing. Thales was incorrect in believing the attraction was due to a magnetic effect, but later science would prove a link between magnetism and electricity.
Information
http://en.wikipedia.org/wiki/Electricity
Science Discovery 2 textbook
Sound by 2E1 Shafiatul
What is sound?
Sound is a vibration or a wave of air molecules which is caused by the motion of an object. The density of the molecules is higher when there is a compression wave. This compression wave travels through the air at the speed depending on the temperature of the surroundings. Since a sound wave contain energy which means it can make things move. But, if the sound wave hits something solid, the wave will bounce back forming an echo. Sound cannot travel through a vacuum. It can only travel through solids, liquids, gases and plasmas.
How is sound being produced?
Sound waves
A series of compressions and rarefactions which changes or waves through the air is called a sound wave. Sound waves vibrate at different rates or frequencies as they move through the air. Frequency is measured in cycles per second, or Hertz (Hz). The faster an object vibrates the higher the pitch of the sound. A frequency of 100 Hz means 100 vibrations every second.
Echolocation
The sound which travels to the walls and is reflected back to our ears is called an echo. Echoes are used to find objects underwater, to find large shoals of fish and to measure the depth of the sea. Animals use echoes to find food and to ‘see’ where they are going. For example, bats. They have a poor sense of sight but a good sense of hearing. They use echolocation to find food. Bats produce a high frequency sound to find insects to eat. This sound then reflects off the insect and travel back to the bat’s ears. This helps the bat to find even the smallest insect. Echolocation also helps the bat to ‘see’ where it is flying.
What affects sound?
Sound vibration
When an object moves or vibrates, sound is produced. There could be no sound without movement. When an object moves or vibrates, the air molecules around it will also vibrate. As long as they are not in a vacuum, vibrating objects produce sound. Each molecule moves back and forwards only in a tiny distance which is enough to cause the air particles to bump into each other. This will create areas where there are many molecules pushed closer. This is called compression. Areas where molecules are spread far apart are called rarefactions. Compressions and rarefactions move outwards away from the sound source in circles.
The speed of sound
Sound will take time to travel. In air, sound travels at a speed of 330 metres per second. In fresh water, sound travels at a speed of 150 metres per second. Sound travels at even higher speeds in solids. For example, an iron sound travels at 5000 metres per second. So, the speed of sound depends on density. The denser the material is the faster the speed of sound.
Examples of stuff producing sound
Here are some examples of things that produce sound:
-A guitar
-A trumpet
-A drum
-A bee (buzzing sound caused by its wings)
-A recorder
-Cars
-Airplanes
And many more.
Sources
http://www.sciencetech.technomuses.ca/english/schoolzone/Info_Sound.cfm
Explore your world with Science discovery 2 (pages 202-206)
http://en.wikipedia.org/wiki/Sound
Sound is a vibration or a wave of air molecules which is caused by the motion of an object. The density of the molecules is higher when there is a compression wave. This compression wave travels through the air at the speed depending on the temperature of the surroundings. Since a sound wave contain energy which means it can make things move. But, if the sound wave hits something solid, the wave will bounce back forming an echo. Sound cannot travel through a vacuum. It can only travel through solids, liquids, gases and plasmas.
How is sound being produced?
Sound waves
A series of compressions and rarefactions which changes or waves through the air is called a sound wave. Sound waves vibrate at different rates or frequencies as they move through the air. Frequency is measured in cycles per second, or Hertz (Hz). The faster an object vibrates the higher the pitch of the sound. A frequency of 100 Hz means 100 vibrations every second.
Echolocation
The sound which travels to the walls and is reflected back to our ears is called an echo. Echoes are used to find objects underwater, to find large shoals of fish and to measure the depth of the sea. Animals use echoes to find food and to ‘see’ where they are going. For example, bats. They have a poor sense of sight but a good sense of hearing. They use echolocation to find food. Bats produce a high frequency sound to find insects to eat. This sound then reflects off the insect and travel back to the bat’s ears. This helps the bat to find even the smallest insect. Echolocation also helps the bat to ‘see’ where it is flying.
What affects sound?
Sound vibration
When an object moves or vibrates, sound is produced. There could be no sound without movement. When an object moves or vibrates, the air molecules around it will also vibrate. As long as they are not in a vacuum, vibrating objects produce sound. Each molecule moves back and forwards only in a tiny distance which is enough to cause the air particles to bump into each other. This will create areas where there are many molecules pushed closer. This is called compression. Areas where molecules are spread far apart are called rarefactions. Compressions and rarefactions move outwards away from the sound source in circles.
The speed of sound
Sound will take time to travel. In air, sound travels at a speed of 330 metres per second. In fresh water, sound travels at a speed of 150 metres per second. Sound travels at even higher speeds in solids. For example, an iron sound travels at 5000 metres per second. So, the speed of sound depends on density. The denser the material is the faster the speed of sound.
Examples of stuff producing sound
Here are some examples of things that produce sound:
-A guitar
-A trumpet
-A drum
-A bee (buzzing sound caused by its wings)
-A recorder
-Cars
-Airplanes
And many more.
Sources
http://www.sciencetech.technomuses.ca/english/schoolzone/Info_Sound.cfm
Explore your world with Science discovery 2 (pages 202-206)
http://en.wikipedia.org/wiki/Sound
Refraction of Light by 2E1 Lee Jae Woong
Refraction
Through our project, I have learnt about refraction and its uses. Refraction refers to the bending of light as it passes between materials of different optical density.
In refraction, I learnt that the denser the material is, the slower the speed of light will be in that material. Refraction will happen when light passes from one medium to another medium with different densities.
For example, when light passes from air to a transparent glass block, the speed of light will slow down and it will cause the light ay to bend closer to the normal.
As seen in diagram 1, the light ray passes from air to a transparent glass block. The light ray, as shown, is bent towards the normal. This indicates that the speed of light is reduced when passing from one medium to another. The denser the medium is, the light ray will bend closer towards the normal. Similarly, when the light ray moves from glass block to air it is refracted away from the normal
Refractive Index
The refractive index of a medium is the measurement of how much the speed of light has reduced or increased inside various types of medium. Generally, the refractive index is subject to changes based on the incidence of the light. This explains why different colours of light travel at different speeds. The higher the index, the slower the speed of light will be through the medium.
Formula for refractive Index is n= sin i / sin r
Effects of Refraction
Effects of refraction can be seen in our everyday lives.
Firstly, refraction causes objects to appear closer than it actually is. For example, in a swimming pool, the pool looks shallower than it actually is. This is because our brains think the light has moved in a straight line. Therefore the swimming pool seems shallower than it usually is. Another example, is when we place our hand below a glass block, our hand seems nearer to the surface than it is. Thus the glass block seems thinner than the actual thickness.
As seen in diagram 2 the pool seems to be of equal depth and it looks shallow. However it is actually deeper than it looks. Due to refraction, swimming pools or ponds always appear to be shallower than they really are. When approaching air from water, the waves speed up and as a result they refract away from the normal.
Diverging rays enter the eye and the brain traces these rays back to where it thinks an image is. This results in a virtual image at a shallower depth than is the actual case.
References
1. Refraction of Light by Rick Reed http://www.ps.missouri.edu/rickspage/refract/refraction.html
2. Explore your world with Science Discovery 2 Textbook
3. Answers.Com http://www.answers.com/topic/refractive-index?cat=technology
4. http://www.asiatravel.com/turkey/istanbul/marinprincesskumburgaz/gifs/pool2.jpg
5. http://pachome2.pacific.net.sg/~ezzychan/refraction.htm
Through our project, I have learnt about refraction and its uses. Refraction refers to the bending of light as it passes between materials of different optical density.
In refraction, I learnt that the denser the material is, the slower the speed of light will be in that material. Refraction will happen when light passes from one medium to another medium with different densities.
For example, when light passes from air to a transparent glass block, the speed of light will slow down and it will cause the light ay to bend closer to the normal.
As seen in diagram 1, the light ray passes from air to a transparent glass block. The light ray, as shown, is bent towards the normal. This indicates that the speed of light is reduced when passing from one medium to another. The denser the medium is, the light ray will bend closer towards the normal. Similarly, when the light ray moves from glass block to air it is refracted away from the normal
Refractive Index
The refractive index of a medium is the measurement of how much the speed of light has reduced or increased inside various types of medium. Generally, the refractive index is subject to changes based on the incidence of the light. This explains why different colours of light travel at different speeds. The higher the index, the slower the speed of light will be through the medium.
Formula for refractive Index is n= sin i / sin r
Effects of Refraction
Effects of refraction can be seen in our everyday lives.
Firstly, refraction causes objects to appear closer than it actually is. For example, in a swimming pool, the pool looks shallower than it actually is. This is because our brains think the light has moved in a straight line. Therefore the swimming pool seems shallower than it usually is. Another example, is when we place our hand below a glass block, our hand seems nearer to the surface than it is. Thus the glass block seems thinner than the actual thickness.
As seen in diagram 2 the pool seems to be of equal depth and it looks shallow. However it is actually deeper than it looks. Due to refraction, swimming pools or ponds always appear to be shallower than they really are. When approaching air from water, the waves speed up and as a result they refract away from the normal.
Diverging rays enter the eye and the brain traces these rays back to where it thinks an image is. This results in a virtual image at a shallower depth than is the actual case.
References
1. Refraction of Light by Rick Reed http://www.ps.missouri.edu/rickspage/refract/refraction.html
2. Explore your world with Science Discovery 2 Textbook
3. Answers.Com http://www.answers.com/topic/refractive-index?cat=technology
4. http://www.asiatravel.com/turkey/istanbul/marinprincesskumburgaz/gifs/pool2.jpg
5. http://pachome2.pacific.net.sg/~ezzychan/refraction.htm
Colours of Light by 2E1 Edgar Wong
How are colors produced?
Colors are produced when a light source hits a prism, which separates the white light into its separate colors are called dispersion.
How to get rainbow colors and to recombine the colors again?
Place a second prism positioned in a way that each other’s points are facing away from each other. Shine the light through both prisms.
What are primary colors?
The three primary colors are the minimum number of colors that can be mixed to make the greatest number of other colors. The primary colors cannot be made by mixing other colors.
Effects of mixing of colors.
When you mix colors together, you will get a different color. If you mix the three primary colors together, you get white.
What do you learn about that particular topic?
I’ve learn about the dispersion of white light by a prism and more about the primary colors.
Summarize the key points of that topic.
Colors, they are produced by white light hitting prisms, when lights separates its called dispersion. Placing two prisms facing away from each other can get and recombine colors. When mixing colors together, you get a different color.
Anything interesting to add?
The spectrum consists of: Red, Orange, Blue, Yellow, Green, Indigo and Violet.
Prisms separate the colors already present in the white light.
Credits.
Science Discovery, Rex M Heyworth, 128, 129 and 130, chapter 8
Color Mixing, Robert Truscio.
Colors are produced when a light source hits a prism, which separates the white light into its separate colors are called dispersion.
How to get rainbow colors and to recombine the colors again?
Place a second prism positioned in a way that each other’s points are facing away from each other. Shine the light through both prisms.
What are primary colors?
The three primary colors are the minimum number of colors that can be mixed to make the greatest number of other colors. The primary colors cannot be made by mixing other colors.
Effects of mixing of colors.
When you mix colors together, you will get a different color. If you mix the three primary colors together, you get white.
What do you learn about that particular topic?
I’ve learn about the dispersion of white light by a prism and more about the primary colors.
Summarize the key points of that topic.
Colors, they are produced by white light hitting prisms, when lights separates its called dispersion. Placing two prisms facing away from each other can get and recombine colors. When mixing colors together, you get a different color.
Anything interesting to add?
The spectrum consists of: Red, Orange, Blue, Yellow, Green, Indigo and Violet.
Prisms separate the colors already present in the white light.
Credits.
Science Discovery, Rex M Heyworth, 128, 129 and 130, chapter 8
Color Mixing, Robert Truscio.
Colours of Light by 2E1 Marcus Choo
Colour :
I have learnt that white light, ( ordinary light ), is a mixture of different colours. When a beam of white light passes through a glass prism, the light splits into seven different colours : Red, Orange, Yellow, Green, Blue, Indigo, Violet. We can get white light back again by combining the colours back together. By using a second prism, or by spinning a colour wheel.
We can see the colours of the spectrum, so it is called the visible spectrum. Some people think the there are only six colours as indigo cannot be easily distinguished from blue and violet.
There are three sections : primary colours, secondary colours and teitary colour. Primary colours consist of : Red, Blue and Green.
Secondary colours consist of : Yellow, Cyan and Magenta.
While teitary colour consist of only : White.
A colour filter is a clear plastic or glass that only lets some colours pass through and absorbs the others.
When white light shines on a colours object, some of the colours in the spectrum are reflected and some are absorbed. We see the colour of the reflected light. The colour of an object is the colour of the light that is reflected from it into our eyes.
When the eye detects light, an image is formed on the retina, ( the back of the eye ). The retina has two kinds of light sensitive cells, they are called the rods and the cones. These cells are connected to a nerve which carries signals to the brain, the brain than interprets the signals as light. The rods do not detect colour, they are sensitive to black and white, and work best in dim light. The cones however, detect colour and work best in bright light.
There are tree types of cone cells, one detects red light, another detects blue light and the other detects green light. This means that these cone cells can detect the three primary colours. When white light shines into the eye, all three types of cones respond. For example the cones which detect red light respond to the red light in the white light and the brain receives signals from all these types of cones and interprets them as white light.
I have learnt that white light, ( ordinary light ), is a mixture of different colours. When a beam of white light passes through a glass prism, the light splits into seven different colours : Red, Orange, Yellow, Green, Blue, Indigo, Violet. We can get white light back again by combining the colours back together. By using a second prism, or by spinning a colour wheel.
We can see the colours of the spectrum, so it is called the visible spectrum. Some people think the there are only six colours as indigo cannot be easily distinguished from blue and violet.
There are three sections : primary colours, secondary colours and teitary colour. Primary colours consist of : Red, Blue and Green.
Secondary colours consist of : Yellow, Cyan and Magenta.
While teitary colour consist of only : White.
A colour filter is a clear plastic or glass that only lets some colours pass through and absorbs the others.
When white light shines on a colours object, some of the colours in the spectrum are reflected and some are absorbed. We see the colour of the reflected light. The colour of an object is the colour of the light that is reflected from it into our eyes.
When the eye detects light, an image is formed on the retina, ( the back of the eye ). The retina has two kinds of light sensitive cells, they are called the rods and the cones. These cells are connected to a nerve which carries signals to the brain, the brain than interprets the signals as light. The rods do not detect colour, they are sensitive to black and white, and work best in dim light. The cones however, detect colour and work best in bright light.
There are tree types of cone cells, one detects red light, another detects blue light and the other detects green light. This means that these cone cells can detect the three primary colours. When white light shines into the eye, all three types of cones respond. For example the cones which detect red light respond to the red light in the white light and the brain receives signals from all these types of cones and interprets them as white light.
Reflection of Light by 2E3 Siti Saiyidah Nafisah
I have learnt that reflection is the bouncing of light off a mirror. A plane mirror is a good reflector of light.
When a ray of light strikes the mirror at a right angle, it is reflected along the same path, called the normal. When a ray of light hits a plane mirror at an angle to the normal (called the angle of incidence), it is reflected at an equal angle but on the opposite side of the normal (angle of reflection). These two angles are always equal no matter how light rays strike the mirror. These are called The Law of Reflection.
In a plane mirror, the image is upright and of the same size as the object. In a plane mirror, the image lies as far behind the mirror as the object is in front of the mirror. Mirrors turn images around from left to right. Hence, in a plane mirror, an image is laterally inverted. An image that cannot be formed on a screen is called a virtual image. In a plane mirror, the image formed is always a virtual image.
There are two types of reflection- Regular reflection and Diffuse reflection.
Textbook Resource: Science Txtbk (pg119-121)
When a ray of light strikes the mirror at a right angle, it is reflected along the same path, called the normal. When a ray of light hits a plane mirror at an angle to the normal (called the angle of incidence), it is reflected at an equal angle but on the opposite side of the normal (angle of reflection). These two angles are always equal no matter how light rays strike the mirror. These are called The Law of Reflection.
In a plane mirror, the image is upright and of the same size as the object. In a plane mirror, the image lies as far behind the mirror as the object is in front of the mirror. Mirrors turn images around from left to right. Hence, in a plane mirror, an image is laterally inverted. An image that cannot be formed on a screen is called a virtual image. In a plane mirror, the image formed is always a virtual image.
There are two types of reflection- Regular reflection and Diffuse reflection.
Textbook Resource: Science Txtbk (pg119-121)
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