11.3 Reflection & Refraction

Question 1

When does total internal reflection occur

Answer 1

When the light is travelling through a medium with a higher refractive index and the angle of incidence at the boundary is greater than the critical angle

Question 2

Define critical angle

Answer 2

When the angle of incidence at the boundary between the 2 medium will produce an angle of refraction of 90 degrees

Question 3

What is an optical fibre

Answer 3

A fibre made of glass which is designed to have varying refractive index so that it can totally internally reflect pulses of visible or infrared light that travels through it

Question 4

State the law of reflection

Answer 4

The angle of incidence is equal to the angle of reflection

Question 5

What causes refraction

Answer 5

When the speed of a wave changes as it passes from one medium to another

Question 6

How do you prove that light that has been reflected off the surface off the surface of water is partially polarised using a pair of Polaroid sunglasses

Answer 6

• by viewing the reflected light through the sunglasses
• if you rotate it the light will grow dimmer
• if you continue to rotate it the light will grow brighter