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REVISION NOTES: PHYSICS 3
LIGHT AND SOUND



Light Reflection

There are a number of different types of mirror. A plane mirror (or flat mirror) will show you an
exact mirror image of yourself if you look into it. Some mirrors bend outwards, these are called
convex mirrors if you look…

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REVISION NOTES: PHYSICS 3
LIGHT AND SOUND





If an object is beyond the principal focus, an inverted image is formed (appears upsidedown) by
the reflected rays. The position and size of the image depends on the distance from the object to the
mirror. The diagram below shows how to use…

Page 3

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REVISION NOTES: PHYSICS 3
LIGHT AND SOUND







Light Refraction

The change of direction in light rays is called light refraction.






Refraction applies to all types of wave, including light and sound. The diagram below demonstrates
refraction using waves of water in a ripple tank:






Light travels slower in glass than…

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REVISION NOTES: PHYSICS 3
LIGHT AND SOUND







Lenses

A lens works by changing the direction of light passing through it. The diagram below shows how a
lens refracts the rays so that they all meet as a point.






Different lens shapes can be tested using:

a converging lens makes parallel…

Page 5

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REVISION NOTES: PHYSICS 3
LIGHT AND SOUND



When the object is nearer to the lens than the principal focus, a magnified virtual image is formed,
but you can only see the image when you look into the lens from the other side to the object. The
lens acts as a…

Page 6

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REVISION NOTES: PHYSICS 3
LIGHT AND SOUND










Sound
Any object which vibrates sends out sound waves
through the air, and vibrates your eardrums so you
hear sound. Sound waves cannot travel through a
vacuum. They are longitudinal waves, so vibrate in the direction they travel in, unlike
electromagnetic waves which…

Page 7

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REVISION NOTES: PHYSICS 3
LIGHT AND SOUND




Humans can hear frequencies between 20Hz and 20,000Hz ­ any sound waves with frequencies
above the human ear are said to be ultrasonic waves. We have many uses for ultrasound.
One example of its use is for ultrasound scanning, used for scanning body…

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