Reflection and refraction

Question 1

Angle of incidence

Answer 1

angle between the normal and the incident ray

Question 2

Specular reflection

Answer 2

Reflection from a smooth, flat surface

Question 3

In specular reflection features

Answer 3

upright

virtual

Question 4

Virtual image

Answer 4

An image from which rays of light appear to come but do not do so in reality.

Question 5

Diffuse reflection

Answer 5

when light is reflected off a surface and is scattered in different directions

Question 6

Refraction

Answer 6

process by which a wave changes speed and sometimes direction upon entering a denser or less dense medium

Question 7

Relationship between the speed of light being transmitted through a material and the density of the substance

Answer 7

the dense the transparent material, the more slowly light travels through it.

Question 8

What will happen to the ray once it passes from air into glass

Answer 8

If the ray meets the boundary at an angle to the normal it bends towards the normal

Question 9

Required practical
Investigate the reflection of light by different types of surface and the refraction of light by different substances

Answer 9

1. Set up a ray box, slit and lens so that a narrow ray of light is produced.
2. Place a 30 centimetre (cm) ruler near the middle of a piece of plain A3 paper. Draw a straight line parallel to its longer sides. Use a protractor to draw a second line at right angles to this line. Label this line with an ‘N’ for ‘normal’.
3. Place the longest side of a rectangular acrylic polymer block against the first line. With the normal near the middle of the block, carefully draw around the block without moving it.
4. Use the ray box to shine a ray of light at the point where the normal meets the block. This is the incident ray.
5. The angle between the normal and the incident ray is called the angle of incidence. Move the ray box or paper to change the angle of incidence. The aim is to see a clear ray reflected from the surface of the block and another clear ray leaving the opposite face of the block.
6. Using a pencil on the paper, mark the path of:
   the incident ray with a cross
   the reflected ray with a cross
   the ray that leaves the block with two crosses - one near the block and the other further away
7. Remove the block. Join the crosses to show the paths of the light rays.
8. Repeat steps 2 to 7 for a rectangular glass block.
9. Measure the angle of incidence, angle of refraction and angle of reflection for each block.

Question 10

Required practical
Investigate the reflection of light by different types of surface and the refraction of light by different substances

Hazard consueqence
and control measures

Answer 10

ray box gets hot
minor burns
do not touch bulb and allow time to cool