Refraction, Why does the light re accelerate?

In summary, refraction is the bending of light as it passes through different mediums. This occurs because light travels at different speeds in different mediums, causing it to change direction. When light enters a denser medium, it slows down and bends towards the normal line, while when it exits a denser medium, it speeds up and bends away from the normal line. This is why light appears to re-accelerate after passing through a lens or other refractive medium. The degree of refraction is determined by the difference in the refractive indices of the two mediums.
  • #1
josh444
3
0
OK, so i think i get why refraction happens and it makes sense that as the light passes into something of a higher refractive index it will decelerate and if it hits at an angle, one "edge" of the beam will hit first and thus descelerate before the other side of the beam causing the beam to bend.

However what i don't understand is why as the beam exits the , let's say block of perspex, and re enters air , the light increases its velocity again causing it to bend. Now I am not contesting the fact that it accelerating would cause it to bend but I am just struggling to understand what is causing the beam to accelerate, as i was under the impresion that upon descelerating it lost some of its kinetic energy (i gues to the block of perspex as heat maybe?) and thefore inorder to accelerate out the other side it would have to regain this kinnetic energy from somewhere and i just don't get where this extra energy comes from.

any one know?

thanks
josh
 
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  • #2
You may want to read our FAQ in this section of PF to get some idea on the nature of optical transport in matter.

Zz.
 
  • #3
ZapperZ said:
You may want to read our FAQ in this section of PF to get some idea on the nature of optical transport in matter.
A most insightful explanation - it is worth a direct link https://www.physicsforums.com/showthread.php?t=104715#4".

AM
 
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FAQ: Refraction, Why does the light re accelerate?

1. What is refraction?

Refraction is the bending of light as it passes through different mediums, such as air, water, or glass. This occurs because light travels at different speeds in different mediums, causing it to change direction.

2. Why does light refract?

Light refracts because of the change in its speed as it passes through different mediums. When light enters a medium with a higher refractive index, it slows down and bends towards the normal line. When it enters a medium with a lower refractive index, it speeds up and bends away from the normal line.

3. How does the angle of incidence affect refraction?

The angle of incidence, which is the angle at which light enters a medium, affects the amount of refraction that occurs. As the angle of incidence increases, the amount of refraction also increases. When the angle of incidence is 0 degrees, there is no refraction.

4. Why does light re-accelerate after refraction?

The speed of light changes as it enters a different medium, but once it exits the medium, it returns to its original speed. This is because the particles in the medium do not permanently absorb or slow down the light, allowing it to return to its original speed and direction.

5. How does the refractive index of a medium affect the amount of refraction?

The refractive index of a medium is a measure of how much the speed of light changes when it travels through that medium. The higher the refractive index, the more the light will bend when it enters that medium. This means that a medium with a higher refractive index will cause more refraction than a medium with a lower refractive index.

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