Physics - P3 - AQA - GCSE - Refractive Index

Refraction - the change in direction when a wave enters a different medium
1. E.G. Air into glass
2. Caused by the change in density in the medium
  1. Changes the speed of the wave
Speed of waves
1. Decrease
  1. Bends towards the normal
2. Increase
  1. Bends away from the normal
3. If the wave hits the medium at 90° (along the normal) it does not refract, but the speed will change.
The normal is a line at an angle of 90° against the surface of the point of entry on the medium.
Refractive index - (when referring to a medium) the ratio of speed of light in a vacuum to speed of light in that medium
1. If an incident ray passes from one medium into another, the angle of refraction of the ray is affected by the refractive index of the material.
2. Refractive index = sin(incident)/sin(refraction)
  1. n=sin i/sin r
  2. Find out the refractive index of the medium below.
    1. n = sin i/sin r
      1. n = sin 55/sin 33
        n = 0.819/0.545
        n = 1.50
        Refractive index is 1.5
    2. What if we knew the refractive index but not the angle of refraction?
      1. n = sin i/sin r
        1.5 = sin 55/sin r
        sin r = sin 55/1.5
        sin r = 0.5461...
        Inverse sin 0.5461... = 33
        r = 33°

Resource summary

	Created by Josh Anderson almost 9 years ago