!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
Showing posts with label 2e2. Show all posts
Showing posts with label 2e2. Show all posts
Friday, June 20, 2008
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.
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
Reflection of Light by 2E2 Andre Lim
Topic: Reflection of light – i. What is reflection of light?
ii. When does it happen?
iii. Types of reflection
iv. Uses of reflection of light, examples?
Reflection is the bouncing of light off a mirror or mirror-like surface. Reflection is also the change in direction of a wave front at an interface between two different media so that the wave front returns into the medium from which it originated from.
A flat mirror called a plane mirror is a good reflector of light. A normal is formed when a ray of light strikes the mirror at a right angle.
-Reflection may even occur on water and clouds
Mainly, there are two types of reflection, specular and diffused.Light being reflected of a smooth surface is Specular. When light strikes this smooth surface, all the reflected rays are in line with each other. An image is formed.
Diffused reflection is reflection from a rough surface. The small bumps and irregularities on a rough surface will cause each of the light rays to reflect n different directions, thus no image is formed.
There are some uses of plane mirrors, for example, plane mirrors helps people to check their appearance, and see things at a certain angle which the eye cannot.
The use of curved mirrors is used to reflect light into microscope to amplify the image’s size and dentist can use it to magnify the image of a patient’s teeth.
Also, if you look place a screen behind the mirror, the image is not formed on the screen. An image that cannot be formed on a screen is known as a virtual image.
Acknowledgement: http://en.wikipedia.org/wiki/Reflection_(physics)#Laws_of_regular_reflection
Sec 2 Science Text Book
Pictures - http://en.wikipedia.org/wiki/Image:Crepuscular_Rays_in_ggp_14.jpg
ii. When does it happen?
iii. Types of reflection
iv. Uses of reflection of light, examples?
Reflection is the bouncing of light off a mirror or mirror-like surface. Reflection is also the change in direction of a wave front at an interface between two different media so that the wave front returns into the medium from which it originated from.
A flat mirror called a plane mirror is a good reflector of light. A normal is formed when a ray of light strikes the mirror at a right angle.
-Reflection may even occur on water and clouds
Mainly, there are two types of reflection, specular and diffused.Light being reflected of a smooth surface is Specular. When light strikes this smooth surface, all the reflected rays are in line with each other. An image is formed.
Diffused reflection is reflection from a rough surface. The small bumps and irregularities on a rough surface will cause each of the light rays to reflect n different directions, thus no image is formed.
There are some uses of plane mirrors, for example, plane mirrors helps people to check their appearance, and see things at a certain angle which the eye cannot.
The use of curved mirrors is used to reflect light into microscope to amplify the image’s size and dentist can use it to magnify the image of a patient’s teeth.
Also, if you look place a screen behind the mirror, the image is not formed on the screen. An image that cannot be formed on a screen is known as a virtual image.
Acknowledgement: http://en.wikipedia.org/wiki/Reflection_(physics)#Laws_of_regular_reflection
Sec 2 Science Text Book
Pictures - http://en.wikipedia.org/wiki/Image:Crepuscular_Rays_in_ggp_14.jpg
Electricity by 2E2 Amruth
What is electricity?
*Electricity is a form of energy and it is convenient as it can be changed into other forms of energy.
What are the effects of electricity on our daily lives?
*We are able to; play games on our computer, travel in cars and other transportations, Watch television, use handphones, etc.
What is the electric current?
*It is the flow of electricity.
What is the electrical circuit?
*It is the path where current moves.
What is the meaning of closed circuit and open circuits?
Closed circuit
*It is a complete path of electricity from one end to the other.
Open circuit
*It is an incomplete path of electricity from one end.
Why are switches used in our daily life?
It is safer way to conduct electricity and to open and close circuits.
What is voltage?
*Voltage is the energy per unit charge.
What is the SI unit for voltage?
*The SI unit for voltage is volt ( V ).
Some interesting stuff…….
*In the times when humans first appeared on Earth, the created electricity by rubbing two materials together.
*The first machine to make an electrical spark was created at 1650; it worked by rubbing a hand on a spinning sulphur ball…. Electricity through friction?
RESOURCES
http://www.historyoftheuniverse.com/electric.html
http://en.wikipedia.org/wiki/Voltage
Book: Explore your world with SCIENCE DISCOVERY 2
Publisher: Pearson Longman
Author : Rex M Heyworth
*Electricity is a form of energy and it is convenient as it can be changed into other forms of energy.
What are the effects of electricity on our daily lives?
*We are able to; play games on our computer, travel in cars and other transportations, Watch television, use handphones, etc.
What is the electric current?
*It is the flow of electricity.
What is the electrical circuit?
*It is the path where current moves.
What is the meaning of closed circuit and open circuits?
Closed circuit
*It is a complete path of electricity from one end to the other.
Open circuit
*It is an incomplete path of electricity from one end.
Why are switches used in our daily life?
It is safer way to conduct electricity and to open and close circuits.
What is voltage?
*Voltage is the energy per unit charge.
What is the SI unit for voltage?
*The SI unit for voltage is volt ( V ).
Some interesting stuff…….
*In the times when humans first appeared on Earth, the created electricity by rubbing two materials together.
*The first machine to make an electrical spark was created at 1650; it worked by rubbing a hand on a spinning sulphur ball…. Electricity through friction?
RESOURCES
http://www.historyoftheuniverse.com/electric.html
http://en.wikipedia.org/wiki/Voltage
Book: Explore your world with SCIENCE DISCOVERY 2
Publisher: Pearson Longman
Author : Rex M Heyworth
Electricity by 2E2 Naqiah
Electricity
Electricity is a form of energy produced by the movement of electrons. Electricity is electrical power or an electric current. This form of energy can be sent through wires in a flow of tiny particles. It is used to produce light and heat and to run motors.
Electricity is a basic feature of all matter, of everything in the universe. Electrical force holds atoms and molecules together. Electricity determines the structure of every object that exists. Together with magnetism, it causes a force called electromagnetism, a fundamental force of the universe. Electricity or electrical signals are essential to many biological processes. In our bodies, electrical signals are carried through the nervous system, moving information to and from the brain. Electrical signals communicate to our brain what the eyes see, what the ears hear, and what the fingers feel.
Electrical signals from our brain causes our muscle movements. Electrical signals cause each heartbeat. One of the most important forms of electricity is in electrical current. During the industrial revolution of the 1800s, people began to find ways to use electricity to do work. Today electricity is used throughout our homes, at work, in communication, in transportation, and in medicine and science.
Electrically powered devices are prevalent. Relatively cheap electricity has made electrical appliances, machines, and other devices possible. A major reason electricity works is because of conductors. First metal, water, tall trees and tall items are good conductors because lightning is attracted to them. These materials have many mobile electrons.
Metal is an easy substance for lightning to travel through so metals are good conductors.However, rubber is a bad conductor because lightning bounces off of it. A bad conductor is called an insulator. An insulator has a few mobile electrons. It is important for us to know the difference between good conductors and insulators because if you're outside in an open field during a storm you will know where to go to be safe from the lightning. Truly, knowing the difference between conductors and insulators of electricity can save our lives.
It is a secondary energy source which means that we get it from the conversion of other sources of energy, like coal, natural gas, oil, nuclear power and other natural sources, which are called primary sources. The energy sources we use to make electricity can be renewable or non-renewable, but electricity itself is neither renewable or non-renewable.
(http://library.thinkquest.org/J001647F/)(http://42explore.com/electric.htm)
Electricity is a form of energy produced by the movement of electrons. Electricity is electrical power or an electric current. This form of energy can be sent through wires in a flow of tiny particles. It is used to produce light and heat and to run motors.
Electricity is a basic feature of all matter, of everything in the universe. Electrical force holds atoms and molecules together. Electricity determines the structure of every object that exists. Together with magnetism, it causes a force called electromagnetism, a fundamental force of the universe. Electricity or electrical signals are essential to many biological processes. In our bodies, electrical signals are carried through the nervous system, moving information to and from the brain. Electrical signals communicate to our brain what the eyes see, what the ears hear, and what the fingers feel.
Electrical signals from our brain causes our muscle movements. Electrical signals cause each heartbeat. One of the most important forms of electricity is in electrical current. During the industrial revolution of the 1800s, people began to find ways to use electricity to do work. Today electricity is used throughout our homes, at work, in communication, in transportation, and in medicine and science.
Electrically powered devices are prevalent. Relatively cheap electricity has made electrical appliances, machines, and other devices possible. A major reason electricity works is because of conductors. First metal, water, tall trees and tall items are good conductors because lightning is attracted to them. These materials have many mobile electrons.
Metal is an easy substance for lightning to travel through so metals are good conductors.However, rubber is a bad conductor because lightning bounces off of it. A bad conductor is called an insulator. An insulator has a few mobile electrons. It is important for us to know the difference between good conductors and insulators because if you're outside in an open field during a storm you will know where to go to be safe from the lightning. Truly, knowing the difference between conductors and insulators of electricity can save our lives.
It is a secondary energy source which means that we get it from the conversion of other sources of energy, like coal, natural gas, oil, nuclear power and other natural sources, which are called primary sources. The energy sources we use to make electricity can be renewable or non-renewable, but electricity itself is neither renewable or non-renewable.
(http://library.thinkquest.org/J001647F/)(http://42explore.com/electric.htm)
Colours of Light by 2E2 Riesky
The colors are being produced when light passes through a prism and dispersion is the separation or splitting of white light into its separate colors.
The most famous example of dispersion is a rainbow, in which dispersion causes the spatial separation of a white light into components of different colors. However, dispersion is the most often explained for light waves, but it possibly occur for any kind of wave that interacts with a medium or passes through an inhomogeneous geometry. On the other hand dispersion also has an impact in my other circumstances.
Ordinary light (white light )is really a mixture of different colors. When a beam of white light passes through a glass prism, the light splits up into the colors you see is a rainbow. These colors are called the spectrum of white light.
The spectrum consists of seven colors: Red, Orange, Yellow, Green, Blue, Indigo and Violet or You can remember the order of the seven colors as a boy’s name: ROY G BIV. As these colors merge one into another gradually, it is difficult to say exactly where one colors ends and the next colors starts.
A rainbow is formed when sunlight (white light) passes through raindrops. These drops of water act as small prisms. The white light separates to form the colors of the spectrum.
Since white light consists of seven colors, we should be able to get white light again by combining the colors together. There are 2 ways:
By using a second prism
Spinning a color wheel
White light and light of other colors can be obtained by mixing just three colors – red, blue and green.
These colors are called the primary colors of light.
There are 2 basic ways colors can be mixed to make other colors. One is by combining color light. Mixing color light is called additive color mixing, because the combined colors are formed by the adding of light from 2 or more light sources together. Two or more lights added together will give more illumination than any of the lights by them selves.
If colored light is mixed together, the brightness of the colored lights are added together. This can be seen where the color illumination overlaps. The yellow mixed from red plus green will be brighter than either the red light or green light alone.
Likewise the color cyan is formed by adding green light and blue light. The cyan is also brighter than its two components.
green light + blue light = cyan
The same goes for the magenta and its mixture of red and blue.
red light + blue light = magenta
White light is formed where all three additive primary colors overlap. Since the white mixture results from the adding of all three color light sources, the white light mixture appears even brighter yet.
PRIMARY COLORS OF LIGHT
By varying the amount of the individual light sources, a full range of colors can be obtained. Television screens and PC monitors use the additive color process.
(http://en.wikipedia.org/wiki/Dispersion_(optics)
(http://home.att.net/~RTRUSCIO/COLORMX.htm)
Text book pg (128, 129 and 130)
The most famous example of dispersion is a rainbow, in which dispersion causes the spatial separation of a white light into components of different colors. However, dispersion is the most often explained for light waves, but it possibly occur for any kind of wave that interacts with a medium or passes through an inhomogeneous geometry. On the other hand dispersion also has an impact in my other circumstances.
Ordinary light (white light )is really a mixture of different colors. When a beam of white light passes through a glass prism, the light splits up into the colors you see is a rainbow. These colors are called the spectrum of white light.
The spectrum consists of seven colors: Red, Orange, Yellow, Green, Blue, Indigo and Violet or You can remember the order of the seven colors as a boy’s name: ROY G BIV. As these colors merge one into another gradually, it is difficult to say exactly where one colors ends and the next colors starts.
A rainbow is formed when sunlight (white light) passes through raindrops. These drops of water act as small prisms. The white light separates to form the colors of the spectrum.
Since white light consists of seven colors, we should be able to get white light again by combining the colors together. There are 2 ways:
By using a second prism
Spinning a color wheel
White light and light of other colors can be obtained by mixing just three colors – red, blue and green.
These colors are called the primary colors of light.
There are 2 basic ways colors can be mixed to make other colors. One is by combining color light. Mixing color light is called additive color mixing, because the combined colors are formed by the adding of light from 2 or more light sources together. Two or more lights added together will give more illumination than any of the lights by them selves.
If colored light is mixed together, the brightness of the colored lights are added together. This can be seen where the color illumination overlaps. The yellow mixed from red plus green will be brighter than either the red light or green light alone.
Likewise the color cyan is formed by adding green light and blue light. The cyan is also brighter than its two components.
green light + blue light = cyan
The same goes for the magenta and its mixture of red and blue.
red light + blue light = magenta
White light is formed where all three additive primary colors overlap. Since the white mixture results from the adding of all three color light sources, the white light mixture appears even brighter yet.
PRIMARY COLORS OF LIGHT
By varying the amount of the individual light sources, a full range of colors can be obtained. Television screens and PC monitors use the additive color process.
(http://en.wikipedia.org/wiki/Dispersion_(optics)
(http://home.att.net/~RTRUSCIO/COLORMX.htm)
Text book pg (128, 129 and 130)
Colours of light by 2E2 Liow Fang Yu
Colours of light
I learnt that sunlight may appear white, but it is actually made up of a mixture of seven colours. When the sunlight passes through the rain drop, the raindrop split the white sunlight into a range or spectrum of colours. The colours that makes the spectrum are red, orange, yellow, green, blue, indigo and violet.
We can see the colours of the spectrum, so it is called the visible spectrum . I learnt that I can also remember the order of the seven colours as a boy’s name: ROY G BIV
I learnt that when the splitting or separation of whit light into a spectrum of colours is called the dispersion of white light.
As the refracted colours of light leave the prism, they are bent again, but not in their original paths. This is because the face of the prism through which the light leaves is not parallel to the face through which it enters.
I learnt that to prove that white light is a mixture of different colours, another prism can be used to recombine the colours of its spectrum. Another way of combining the different colours of a spectrum is by spinning a rainbow-coloured disc called Newton’s disc.
I learnt that when a white light is a mixture of different colours, another prism can be used to recombine the colours of its spectrum. I learnt that white light and light of other colours can be obtained by lust mixing three colours. These three colours are red, blue and green. These three colours are called the primary colours of light.
Mixing the primary colours two at a time gives the following colours:
RED + BLUE = MAGENTA
RED + GREEN = YELLOW
BLUE + GREEN = CYAN
A colour television works in the same way. The picture on the television screen is made of dots of coloured light. A mixture of red, green and blue dots in different combinations and varying amounts of brightness produces the different colours in the picture.
These information can be found in : Interactive Science 2 (book) pg113 to119 and
Explore your world with science discovery 2 (book) pg128 to 130.
I learnt that sunlight may appear white, but it is actually made up of a mixture of seven colours. When the sunlight passes through the rain drop, the raindrop split the white sunlight into a range or spectrum of colours. The colours that makes the spectrum are red, orange, yellow, green, blue, indigo and violet.
We can see the colours of the spectrum, so it is called the visible spectrum . I learnt that I can also remember the order of the seven colours as a boy’s name: ROY G BIV
I learnt that when the splitting or separation of whit light into a spectrum of colours is called the dispersion of white light.
As the refracted colours of light leave the prism, they are bent again, but not in their original paths. This is because the face of the prism through which the light leaves is not parallel to the face through which it enters.
I learnt that to prove that white light is a mixture of different colours, another prism can be used to recombine the colours of its spectrum. Another way of combining the different colours of a spectrum is by spinning a rainbow-coloured disc called Newton’s disc.
I learnt that when a white light is a mixture of different colours, another prism can be used to recombine the colours of its spectrum. I learnt that white light and light of other colours can be obtained by lust mixing three colours. These three colours are red, blue and green. These three colours are called the primary colours of light.
Mixing the primary colours two at a time gives the following colours:
RED + BLUE = MAGENTA
RED + GREEN = YELLOW
BLUE + GREEN = CYAN
A colour television works in the same way. The picture on the television screen is made of dots of coloured light. A mixture of red, green and blue dots in different combinations and varying amounts of brightness produces the different colours in the picture.
These information can be found in : Interactive Science 2 (book) pg113 to119 and
Explore your world with science discovery 2 (book) pg128 to 130.
Electricity by 2E2 Siti Azwani
Electricity
i) I have learnt that electricity is a controllable and convenient form of energy used in everyday life. Electricity is the flow of electrons. Without it, we may not be able to perform our everyday routine. Mainly, we used electricity for work, play, in the house and at work, (and at school).
ii) Electricity is a basic part of nature and it is one of our most widely used forms of energy. We get electricity, which is a secondary energy source, from the conversion of other sources of energy, like coal, natural gas, oil, nuclear power and other natural sources, which are called primary sources.
In every electricity, there will always be an electric current. An electric current is a flow of electric charge around a circuit. The charge is already in the wires. This charge is evenly spread out through the wires. As soon as you close the switch, the cell starts to push on the charge. So all the charge starts moving at once. An electric cell gives energy to the electrons and pushes them around a circuit.
Voltage is a measure of how much energy the electrons receive.
iv) acknowledge from: sec 2 Science textbook and wikipedia.com
i) I have learnt that electricity is a controllable and convenient form of energy used in everyday life. Electricity is the flow of electrons. Without it, we may not be able to perform our everyday routine. Mainly, we used electricity for work, play, in the house and at work, (and at school).
ii) Electricity is a basic part of nature and it is one of our most widely used forms of energy. We get electricity, which is a secondary energy source, from the conversion of other sources of energy, like coal, natural gas, oil, nuclear power and other natural sources, which are called primary sources.
In every electricity, there will always be an electric current. An electric current is a flow of electric charge around a circuit. The charge is already in the wires. This charge is evenly spread out through the wires. As soon as you close the switch, the cell starts to push on the charge. So all the charge starts moving at once. An electric cell gives energy to the electrons and pushes them around a circuit.
Voltage is a measure of how much energy the electrons receive.
iv) acknowledge from: sec 2 Science textbook and wikipedia.com
Reflection of Light by 2E2 Elizabeth Lee
Topic: Reflection of light – i. What is reflection of light?
ii. When does it happen?
iii. Types of reflection
iv. Uses of reflection of light, examples?
I have learnt that reflection is the bouncing of light off a mirror surface.
Reflection is also the change in direction of a wave front at an interface between two different media so that the wave front returns into the medium from which it originated.
There are two types of reflection, specular and diffused.
Specular reflection is reflection from a smooth surface. When light strikes this smooth surface, all the reflected rays are in line with each other. An image is formed.
Diffused reflection is reflection from a rough surface. The small bumps and irregularities on a rough surface will cause each of the light rays to reflect n different directions. No image is formed.
Characteristics of Reflection are that the image formed is the same size and shape of the object. It is also a virtual image.
Acknowledgement: http://en.wikipedia.org/wiki/Reflection_(physics)#Laws_of_regular_reflection
http://library.thinkquest.org/27356/p_reflection.htm
ii. When does it happen?
iii. Types of reflection
iv. Uses of reflection of light, examples?
I have learnt that reflection is the bouncing of light off a mirror surface.
Reflection is also the change in direction of a wave front at an interface between two different media so that the wave front returns into the medium from which it originated.
There are two types of reflection, specular and diffused.
Specular reflection is reflection from a smooth surface. When light strikes this smooth surface, all the reflected rays are in line with each other. An image is formed.
Diffused reflection is reflection from a rough surface. The small bumps and irregularities on a rough surface will cause each of the light rays to reflect n different directions. No image is formed.
Characteristics of Reflection are that the image formed is the same size and shape of the object. It is also a virtual image.
Acknowledgement: http://en.wikipedia.org/wiki/Reflection_(physics)#Laws_of_regular_reflection
http://library.thinkquest.org/27356/p_reflection.htm
Thursday, June 19, 2008
Sound by 2E2 Syafiqah
I've learnt something about sound from the sources i had taken and studied,such as borrow books at the library, looking at the science textbook and also searching information on the internet. What i've learnt? I've learnt that sound is a type of energy that were produced when an object vibrates.
Why do we hear sounds?
Humans have three parts, the outer ear, the middle ear and the inner ear.
What does the outer ear do? It collects and funnels the sound to the middle ear. Between the outer ear and the middles ear is a membrane called the eardrum.
What cause the eardrum vibrate?
Sound waves cause the eardrum to vibrate. When the eardrum vibrates, it touches the first of the three tiny bones in the middle ear. This bone vibrates and cause the other two bones to vibrate.
( source taken by book physical science in depth and http://www.worsleyschool.net/science/files/sound/energy.html )
Why do we hear sounds?
Humans have three parts, the outer ear, the middle ear and the inner ear.
What does the outer ear do? It collects and funnels the sound to the middle ear. Between the outer ear and the middles ear is a membrane called the eardrum.
What cause the eardrum vibrate?
Sound waves cause the eardrum to vibrate. When the eardrum vibrates, it touches the first of the three tiny bones in the middle ear. This bone vibrates and cause the other two bones to vibrate.
( source taken by book physical science in depth and http://www.worsleyschool.net/science/files/sound/energy.html )
Sound by 2E2 Rosalind
I learnt What is Sound and What are Sound Waves.
Sound is a type of energy. It is a vibration that travels through the surroundings and enters our ears as sound .
Sound waves are waves which radiate out from their source in circles. The particles of air in the wave move backward and forwards in the same direction as the sound is travelling. These bands of compression and rarefaction move along the spring. This is how s sound wave moves through air, water or solid materials.
Sounds needs to travel through a medium, such as a gas, a liquid or a solid. It cannot travel through a vacuum. This is because sound is a form of energy. In order for sound to move it has to tranfer its energy from one particle to another. If there are no particles, sound cannot travel.
Sound waves are invisible to us, but they can be represented by a machine called an Oscilloscope.
(source taken from book: physical sound IN DEPTH, SOUND)
Sound is a type of energy. It is a vibration that travels through the surroundings and enters our ears as sound .
Sound waves are waves which radiate out from their source in circles. The particles of air in the wave move backward and forwards in the same direction as the sound is travelling. These bands of compression and rarefaction move along the spring. This is how s sound wave moves through air, water or solid materials.
Sounds needs to travel through a medium, such as a gas, a liquid or a solid. It cannot travel through a vacuum. This is because sound is a form of energy. In order for sound to move it has to tranfer its energy from one particle to another. If there are no particles, sound cannot travel.
Sound waves are invisible to us, but they can be represented by a machine called an Oscilloscope.
(source taken from book: physical sound IN DEPTH, SOUND)
Sound by 2E2 Shayidah
I have learnt that Sound is a vibration.
When something makes a noise it is vibrating,and this causes air molecules around it to vibrate too.
These vibrations are transmitted through the air, to our ears, where we preceive them as sound.
Do you know that Thunder is one of nature's loudest sounds!
A nearby thunderclap may reach 120 decibals,equiralent to being within 60 metres of a jet aircraft during take-off.
Volcano eruptions may be the loudest commonly occuring Sounds on Earth,at over 272 dB.
When something makes a noise it is vibrating,and this causes air molecules around it to vibrate too.
These vibrations are transmitted through the air, to our ears, where we preceive them as sound.
Do you know that Thunder is one of nature's loudest sounds!
A nearby thunderclap may reach 120 decibals,equiralent to being within 60 metres of a jet aircraft during take-off.
Volcano eruptions may be the loudest commonly occuring Sounds on Earth,at over 272 dB.
Sound by 2E2 Diyana
We did on the topic 'Sounds'.I learnt the particular topic in our school science textbook and borrowed some books from the library.I also did some research in the internet about sounds.
Sound is made when something vibrates, it moves back and forth.A vibrating object could be a speaker on a CD player, or your vocal cords or even the strings on a guitar.
As it vibrates, it pushes the air molecules next to it closer together, in patterns corresponding to the movements of the object.
Sound can also be used to do useful jobs. For example; Sound waves sent into the womb of a pegnant woman will be deflected in patterns representing the outline of the fetus within.
(Source taken from www.yahoo.com)
Colours of Light by 2E2 Lee Yen Ting
Colours of light.
I learnt that when a beam of white light passes through a glass prism, the light splits up into the colours we in a rainbow. These colours are called the spectrum of white lights. Dispersion of light is when the separation or splitting of white light into its separate colours.
White light consists of seven colours, we should be able to get white light again by combining the colours together. Here are the ways:
One is by spinning a colours wheel: when the wheel is turned quickly, the colours appear to mix and the wheel looks white.
Primary colours are colours that can be obtained by mixing with just three colours – red, Blue and green. Mixing all three primary colours gives white light.
By mixing the primary colours two at a time gives the following colours:
Red + Blue = magenta
Red + green = yellow
Blue + green = cyan
The key points is that Rainbow is formed when a beam of white light passes through a glass prism and the light splits up into the colours we see in a rainbow. Light of different colours can be mixed together to produce other colours.
The spectrum consists of seven colours: Red, Orange, Yellow, Green, Blue, Indigo and Violet. We could remember the order as a boy’s name: ROY G BIV.
These colours formed as a colour wheel and when the colours wheel spins, the colours appear to mix and the wheel looks white as mention above how to combine the colours together to get white light again.
These information can be found in Explore Your World with SCIENCE DISCOVERY 2 page 128 – 130.
I learnt that when a beam of white light passes through a glass prism, the light splits up into the colours we in a rainbow. These colours are called the spectrum of white lights. Dispersion of light is when the separation or splitting of white light into its separate colours.
White light consists of seven colours, we should be able to get white light again by combining the colours together. Here are the ways:
One is by spinning a colours wheel: when the wheel is turned quickly, the colours appear to mix and the wheel looks white.
Primary colours are colours that can be obtained by mixing with just three colours – red, Blue and green. Mixing all three primary colours gives white light.
By mixing the primary colours two at a time gives the following colours:
Red + Blue = magenta
Red + green = yellow
Blue + green = cyan
The key points is that Rainbow is formed when a beam of white light passes through a glass prism and the light splits up into the colours we see in a rainbow. Light of different colours can be mixed together to produce other colours.
The spectrum consists of seven colours: Red, Orange, Yellow, Green, Blue, Indigo and Violet. We could remember the order as a boy’s name: ROY G BIV.
These colours formed as a colour wheel and when the colours wheel spins, the colours appear to mix and the wheel looks white as mention above how to combine the colours together to get white light again.
These information can be found in Explore Your World with SCIENCE DISCOVERY 2 page 128 – 130.
Colours of light by 2E2 Billy A.
How are colours being produced? The colour are produced when light pass through a prism. The process is called dispersion. The most familiar example of dispersion is probably a rainbow, in which dispersion causes the spatial separation of a white light into components of different wavelengths (different colors).
However, dispersion also has an impact in many other circumstances: for example, it causes pulses to spread in optical fibers, degrading signals over long distances; also, a cancellation between dispersion and nonlinear effects leads to soliton waves. Dispersion is most often described for light waves, but it may occur for any kind of wave that interacts with a medium or passes through an inhomogeneous geometry (e.g. a waveguide), such as sound waves. Dispersion is sometimes called chromatic dispersion to emphasize its wavelength-dependent nature.
Sunlight is often called white light, since it is a combination of all the visible colours. Since the index of refraction is different for each colour, the angle of refraction will be different for each colour when the light passes from air into glass or other transparent material. This is according to Snell's Law. (See Snell's Law for the Refraction of Light for more information.)
Now if the piece of glass has parallel sides--such as with a window--the light will return in the same direction that it entered the material. But if the material is shaped like a prism, the angles for each colour will be exaggerated, and the colours will be displayed as a spectrum of light
The visible colours are in the order of the spectrum. You can remember the order by the name ROY G. BIV. Note that in the illustration above, the colours are distinctly separated. In realty, they blend into each other, such that there are colours in between. For example, there is red-orange in between red and orange. To get it back just reverse the process.
The primary colours red, blue, and green. these colours are then mixed to make secondary colours and if the three colours are mixed, it will make the colour white.
In optics and physics, Snell's law (also known as Descartes' law or the law of diffraction), is a formula used to describe the relationship between the angles of incidence and refraction, when referring to light or other waves, passing through a boundary between two different isotropic media, such as water and glass. The law says that the ratio of the sine’s of the angles of incidence and of refraction is a constant that depends on the media.
In optics, the law is used in ray tracing to compute the angles of incidence or refraction, and in experimental optics to find the refractive index of a material.
Refraction of light at the interface between two media of different refractive indices, with n2 > n1. Since the velocity is lower in the second medium (v2 < v1), the angle of refraction θ2 is less than the angle of incidence θ1; that is, the ray in the higher-index medium is closer to the normal.
Named after Dutch mathematician Willebrord Snellius, one of its discoverers,
Snell's law states that the ratio of the sine’s of the angles of incidence and refraction is equivalent to the ratio of velocities in the two media, or equivalent to the opposite ratio of the indices of refraction:
or
Snell's law follows from Fermat's principle of least time, which in turn follows from the propagation of light as waves.
SOURCE
-wikipedia
-books
-encarta
-my brain
However, dispersion also has an impact in many other circumstances: for example, it causes pulses to spread in optical fibers, degrading signals over long distances; also, a cancellation between dispersion and nonlinear effects leads to soliton waves. Dispersion is most often described for light waves, but it may occur for any kind of wave that interacts with a medium or passes through an inhomogeneous geometry (e.g. a waveguide), such as sound waves. Dispersion is sometimes called chromatic dispersion to emphasize its wavelength-dependent nature.
Sunlight is often called white light, since it is a combination of all the visible colours. Since the index of refraction is different for each colour, the angle of refraction will be different for each colour when the light passes from air into glass or other transparent material. This is according to Snell's Law. (See Snell's Law for the Refraction of Light for more information.)
Now if the piece of glass has parallel sides--such as with a window--the light will return in the same direction that it entered the material. But if the material is shaped like a prism, the angles for each colour will be exaggerated, and the colours will be displayed as a spectrum of light
The visible colours are in the order of the spectrum. You can remember the order by the name ROY G. BIV. Note that in the illustration above, the colours are distinctly separated. In realty, they blend into each other, such that there are colours in between. For example, there is red-orange in between red and orange. To get it back just reverse the process.
The primary colours red, blue, and green. these colours are then mixed to make secondary colours and if the three colours are mixed, it will make the colour white.
In optics and physics, Snell's law (also known as Descartes' law or the law of diffraction), is a formula used to describe the relationship between the angles of incidence and refraction, when referring to light or other waves, passing through a boundary between two different isotropic media, such as water and glass. The law says that the ratio of the sine’s of the angles of incidence and of refraction is a constant that depends on the media.
In optics, the law is used in ray tracing to compute the angles of incidence or refraction, and in experimental optics to find the refractive index of a material.
Refraction of light at the interface between two media of different refractive indices, with n2 > n1. Since the velocity is lower in the second medium (v2 < v1), the angle of refraction θ2 is less than the angle of incidence θ1; that is, the ray in the higher-index medium is closer to the normal.
Named after Dutch mathematician Willebrord Snellius, one of its discoverers,
Snell's law states that the ratio of the sine’s of the angles of incidence and refraction is equivalent to the ratio of velocities in the two media, or equivalent to the opposite ratio of the indices of refraction:
or
Snell's law follows from Fermat's principle of least time, which in turn follows from the propagation of light as waves.
SOURCE
-wikipedia
-books
-encarta
-my brain
Refraction of Light by 2E2 Chee Hui Juan
REFRACTION OF LIGHT
Qn: What is refraction of light?
Refraction is the bending of light due to the change of its speed when it passes from one medium to another of a different optical densities.
Qn: When does it happen? How and when will light bend?
The bending occurs because the speed in which light travels through a substance depends on the substance’s density. Light only bends when it passes from a substances of one density into a substances of a different density. Since light travels slower in water then in air, water is said to have a greater optical density than air.
Qn: What it refractive index?
It is the ratio of speed in light in vacuum and speed of light in the material.
Qn: Effects of refraction?
Bending of objects
Objects partially submerged in water appear bent, shifted and magnified.
Apparent thickness
Glass blocks appear less thick than they actually are.
Apparent depth
Swimming pools appear shallower than they actually are.
Apparent position
At dawn or dusk, then Sun appears to be above the horizon at its apparent position for about four minutes longer than it really is.
Source; textbook resource and http://en.wikipedia.org/wiki/Refraction
Qn: What is refraction of light?
Refraction is the bending of light due to the change of its speed when it passes from one medium to another of a different optical densities.
Qn: When does it happen? How and when will light bend?
The bending occurs because the speed in which light travels through a substance depends on the substance’s density. Light only bends when it passes from a substances of one density into a substances of a different density. Since light travels slower in water then in air, water is said to have a greater optical density than air.
Qn: What it refractive index?
It is the ratio of speed in light in vacuum and speed of light in the material.
Qn: Effects of refraction?
Bending of objects
Objects partially submerged in water appear bent, shifted and magnified.
Apparent thickness
Glass blocks appear less thick than they actually are.
Apparent depth
Swimming pools appear shallower than they actually are.
Apparent position
At dawn or dusk, then Sun appears to be above the horizon at its apparent position for about four minutes longer than it really is.
Source; textbook resource and http://en.wikipedia.org/wiki/Refraction
Refraction of Light by 2E2 Edna Chew
Refraction of Light
Refraction is the bending of a wave when it enters a medium where its speed is different. The refraction of light when it passes from a fast medium to a slow medium bends the light ray toward the normal to the boundary between the two media.
If you have ever half submerged a pen into water, you have probably noticed that the pen appears bent at the point it enters the water.
This optical effect is due to refraction.
When light travels through air it travels at 186,000 miles per second. As the light encounters a water surface some of the light is reflected and some of the light passes into the water. Upon entering the water, however, the light slows down by 46,000 miles per second. This change in speed causes the direction of the light ray to change. When we look at a pencil in a glass of water the light from the pencil in the water is being refracted, so it appears in a different location.
How refraction happens depends on the refractive index of the mediums and the angle between the light ray and the line perpendicular (normal) to the surface separating the two mediums (medium/medium interface).
The angle between the light ray and the normal as it leaves a medium is called the angle of incidence. The angle between the light ray and the normal as it enters a medium is called the angle of refraction.
When light passes from a substance of lower optical density to a substance of higher optical density the light is refracted at a smaller angle relative to the normal. (Figure 1)
When light passes from a substance of higher optical density to a substance of lower optical density the light is refracted a larger angle relative to the normal. (Figure 2)
Figure 1 Figure 2
Refraction is also responsible for rainbows and for the splitting of white light into a rainbow-spectrum as it passes through a glass prism. Glass has a higher refractive index than air and the different frequencies of light travel at different speeds (dispersion), causing them to be refracted at different angles, so that you can see them. The different frequencies correspond to different colors observed.
While refraction allows for beautiful phenomena such as rainbows, it may also produce peculiar optical phenomena, such as mirages and Fata Morgana. These are caused by the change of the refractive index of air with temperature.
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.
The refractive index n of a medium is defined as the ratio of the phase velocityc of a wave phenomenon such as light or sound in a reference medium to the phase velocity vp in the medium itself:
Acknowledgement:
http://en.wikipedia.org/
http://library.thinkquest.org/27066/lightrays/nlrefraction.html
http://www.ps.missouri.edu/rickspage/refract/refraction.html
http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/refr.html
http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/opt/mch/refr/more.rxml
Refraction is the bending of a wave when it enters a medium where its speed is different. The refraction of light when it passes from a fast medium to a slow medium bends the light ray toward the normal to the boundary between the two media.
If you have ever half submerged a pen into water, you have probably noticed that the pen appears bent at the point it enters the water.
This optical effect is due to refraction.
When light travels through air it travels at 186,000 miles per second. As the light encounters a water surface some of the light is reflected and some of the light passes into the water. Upon entering the water, however, the light slows down by 46,000 miles per second. This change in speed causes the direction of the light ray to change. When we look at a pencil in a glass of water the light from the pencil in the water is being refracted, so it appears in a different location.
How refraction happens depends on the refractive index of the mediums and the angle between the light ray and the line perpendicular (normal) to the surface separating the two mediums (medium/medium interface).
The angle between the light ray and the normal as it leaves a medium is called the angle of incidence. The angle between the light ray and the normal as it enters a medium is called the angle of refraction.
When light passes from a substance of lower optical density to a substance of higher optical density the light is refracted at a smaller angle relative to the normal. (Figure 1)
When light passes from a substance of higher optical density to a substance of lower optical density the light is refracted a larger angle relative to the normal. (Figure 2)
Figure 1 Figure 2
Refraction is also responsible for rainbows and for the splitting of white light into a rainbow-spectrum as it passes through a glass prism. Glass has a higher refractive index than air and the different frequencies of light travel at different speeds (dispersion), causing them to be refracted at different angles, so that you can see them. The different frequencies correspond to different colors observed.
While refraction allows for beautiful phenomena such as rainbows, it may also produce peculiar optical phenomena, such as mirages and Fata Morgana. These are caused by the change of the refractive index of air with temperature.
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.
The refractive index n of a medium is defined as the ratio of the phase velocityc of a wave phenomenon such as light or sound in a reference medium to the phase velocity vp in the medium itself:
Acknowledgement:
http://en.wikipedia.org/
http://library.thinkquest.org/27066/lightrays/nlrefraction.html
http://www.ps.missouri.edu/rickspage/refract/refraction.html
http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/refr.html
http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/opt/mch/refr/more.rxml
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