Reflection and refraction

Question 1

the normal

Answer 1

a line drawn at 90 degrees to the mirror surface at the point that the arriving/incident ray meets the mirror

angles r and i are measured from this line

Question 2

angle i and r

Answer 2

angle of incidence (between the incident ray and the normal)

angle of reflection/refraction (between the reflected ray and the normal)

Question 3

incident ray and reflected ray

Answer 3

the ray of light that meets the mirror/substance

the reflected ray of light

Question 4

law of reflection

Answer 4

angle i = angle r

Question 5

refraction

Answer 5

change in direction of a light ray when it travels from one transparent material into another

Question 6

Describe the effect of density on light rays in regards to the angle of incidence and reflection and wave speed

Answer 6

when light enters a more dense substance it bends towards the normal and slows down

when light enters a less dense substance it bends away from the normal and speeds up

Question 7

What happens if a ray of light meets a material at 90 degrees?

Answer 7

nothing, it travels along the normal so the direction doesn’t change

Question 8

Why does refraction happen?

Answer 8

because light waves travel at different directions at different speeds in different materials

Question 9

State the law of reflection [1]

Answer 9

the angle of incidence is equal to the angle of reflection

Question 10

Explain what happens during refraction [3]

Answer 10

the speed of the wave changes as it moves from one medium to another

its direction also changes unless it is travelling along the normal

Question 11

A ray of light strikes a plane mirror at 42 degrees to the normal.

State the angle of reflection [1]

Answer 11

42 degrees

Question 12

A ray of light is travelling through a glass block before entering into air. The angle of incidence in the glass block is 34 degrees.

Estimate the angle of refraction once it has entered the air and give a reason [2]

Answer 12

greater than 34 as it speeds up and bends away from the normal

(e.g. 45 degrees)

Question 13

State the factors that influence the angle of refraction for a material [2]

Answer 13

the ratio of refractive indices wither side of the boundary

the optical density of the material

material and speed of waves in different materials

Question 14

Describe how each of these change during refraction:

a) wave speed [2]
b) wavelength [2]
c) frequency [1]

Answer 14

a) speeds up when moving from more to less dense medium
b) decreases when moving from less dense to more dense material
c) no change