P14 Light

Question 1

Angles during reflection:

Answer 1

Angle of incidence = Angle of reflection

Angle between RAY and NORMAL

Question 2

What is specular reflection?

Answer 2

All light rays are reflected in the same direction ( θi = θr), and an image is produced.
This takes place on smooth/polished surfaces

Question 3

What is diffuse reflection?

Answer 3

Light rays are scattered, as not every light ray is reflected at the same angle. Diffuse reflection doesn’t produce an image, and occurs on rough surfaces

Question 4

Describe how filters work

Answer 4

They absorb certain wavelengths of light and transmit others

Question 5

Describe how opaque objects seem colourful

Answer 5

They absorb some wavelengths and reflect others, e.g. an apple reflects red light and absorbs all other wavelengths

Question 6

Describe transparent, translucent and opaque

Answer 6

Transparent - can see through, as they transmit virtually all wavelengths of light
Translucent - Light is partially scattered and cannot see through clearly - image isn’t seen
Opaque - Can’t see through at all

Question 7

Identify one risk assessment when using a ray box, and provide a solution

Answer 7

It can get hoy, so turn it off when not in use

Question 8

Is the angle of refraction the same for all materials

Are the angles of incidence and reflection the same for all materials

Answer 8

No

Yes

Question 9

Describe 2 ways in which a lens can be made more powerful

Answer 9

• Making it more curved

- Using a different material (That refracts light more strongly)

Question 10

What is an image

Answer 10

The point where all light rays from a particular point on an object appear to come together

Question 11

Explain what causes translucence

Answer 11

A material having many internal boundaries, which change the direction of the light repeatedly

Question 12

Describe an experiment to test the law of reflection using a ray box and a mirror

Answer 12

draw straight line XY on white paper and use protractor to draw ‘normal’
perpendicular to XY,
place mirror exactly on XY and direct light at point P where normal
intersects XY using ray box,
adjust direction of light ray so angle of incidence ≈ 10°, mark direction of
incident and reflected rays,
remove mirror and use protractor to measure angles of incidence and
reflection,
repeat for different angles of incidence,
record all results in table, results should show angle of incidence =
angle of reflection