Why does the direction of light change during refraction if the speed

In summary, during refraction, the direction of light changes because the speed of the wave changes when it passes through a different medium. This applies to any wave, not just light, and is due to the relationship between frequency, wavelength, and speed. The change in direction occurs to maintain the frequency-wavelength relationship.
  • #1
rahuljayanthb
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why does the direction of light change during refraction if the speed changes?how are speed and direction related?
 
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  • #2
welcome to pf!

hi rahuljayanthb! welcome to pf! :wink:

rahuljayanthb said:
why does the direction of light change during refraction if the speed changes?how are speed and direction related?

it's because light is a wave

in fact, it applies to any wave … for example, the direction of an earthquake wave will change when it goes through a boundary between rocks with a different speed of sound

the frequency stays the same (that's obvious, isn't it?), and frequency times wavelength = speed, so if speed decreases, then wavelength must decrease, so the waves must get closer together, and the only way of doing that is to bend away from the perpendicular :smile:
 
  • #3


Just to illustrate what tiny-tim said, here is a video of a simulation (YouTube).

Notice that the distance between lines in incoming wave (wavelength) is longer than in the wave that passed into material (there is also a reflected wave going back up), but the lines still match at the boundary. That forces a change of the direction angle.
 

FAQ: Why does the direction of light change during refraction if the speed

1. Why does light change direction during refraction?

Light changes direction during refraction because it travels through different mediums with varying optical densities. When light passes from one medium to another, its speed changes, causing it to bend or change direction.

2. How does the speed of light relate to its direction during refraction?

The speed of light is directly related to its direction during refraction. As light travels through different mediums, its speed changes, causing it to bend or change direction. The higher the difference in optical density between the mediums, the greater the change in direction.

3. Does the wavelength of light affect its direction during refraction?

Yes, the wavelength of light does affect its direction during refraction. This is because the speed of light is dependent on the medium it travels through, and different wavelengths of light interact with mediums differently, causing them to refract at different angles.

4. Why does light slow down when it travels through a medium?

Light slows down when it travels through a medium due to the interactions between the photons of light and the particles of the medium. These interactions cause the light to be absorbed and re-emitted, which slows down its overall speed.

5. How does the angle of incidence affect the direction of light during refraction?

The angle of incidence, or the angle at which light enters a medium, directly affects the direction of light during refraction. The greater the angle of incidence, the greater the change in direction of the light as it passes through the medium. This is due to the change in speed of light as it enters the new medium.

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