Waves - Light and Sound

Question 1

what type of waves are light?

Answer 1

transverse waves which can be reflected and refracted

Question 2

what is the law of reflection?

Answer 2

the angle of incidence equals the angle of reflection

Question 3

how would you investigate the refraction of light, using rectangular blocks, semi-circular blocks and triangular prisms?

Answer 3

• place a block of glass on a piece of paper, and draw its outline
• shine the light ray through the glass block
• use crosses to mark the path of the ray.
• join up crosses with a ruler
• draw on a normal where the ray enters the glass block
• measure the angle of incidence and the angle of refraction and add these to your results table
• comment on how the speed of the light has changed as the light moves between the mediums
• repeat this for different angles of incidence and different glass prisms.

Question 4

what is the relationship between refractive index, angle of incidence and angle of refraction?

Answer 4

refractive index = sin(angle of incidence)/sin(angle of refraction)

Question 5

how would you investigate the refractive index of glass, using a glass block?

Answer 5

• place a glass block onto a sheet of white paper and draw around the block
• shine the light ray through the glass block
• use crosses to mark the path of the ray.
• join up crosses with a ruler
• draw on a normal where the ray enters the glass block
• measure the angle of incidence and the angle of refraction and add these to your results table
• calculate the refractive index
• repeat using a different angle of incidence
• find an average of your results

Question 6

what is total internal reflection used for?

Answer 6

to transmit signals along optical fibres

Question 7

what is critical angle?

Answer 7

the angle of incidence which produces an angle of refraction of 90 degrees

Question 8

what is total internal reflection?

Answer 8

when the angle of incidence is greater than the critical angle, total internal reflection occurs and all light is reflected at the boundary

Question 9

when does total internal reflection occur?

Answer 9

at a boundary from a high refractive index material to a low refractive index material

Question 10

what is the relationship between critical angle and refractive index?

Answer 10

refractive index = 1/sin(critical angle)

Question 11

what type of waves are sound waves?

Answer 11

longitudinal waves which can be reflected and refracted