Refractive index & Snell's law

A student is investigating the refraction of light by a rectangular glass block. The glass block is surrounded by air. The diagram below shows the path of the light as it enters the block, when it is refracted within the block and when it exits the block.

Which statement is correct?

A The angles and are the same because the glass block is surrounded by air.

B The product of sin and the refractive index of glass is a constant.

C The refractive index of glass is less than the refractive index of air.

D The speed of light is the same in both air and glass.

Your answer

The normal frequency range of hearing for young people is from 20 Hz to 20 kHz.

Describe how you can use an oscilloscope, and other additional laboratory equipment, to determine the actual upper limit of the frequency range for a young person.

State one difference and one similarity between the oscillations of a stationary sound wave and a progressive sound wave.

You are provided with a ray-box, a semi-circular block of plastic and other normal laboratory equipment. The outline of the block is shown below.

Describe how you could measure the refractive index n of the block using the critical angle method. Draw on the diagram and label it to make your answer clear.

Which of the following statements is/are correct about electromagnetic waves?

1 They can be plane polarised. 2 They can be refracted and diffracted. 3 They have the same speed in a vacuum and in glass.

A Only 1

B Only 3

C Only 1 and 2

D 1, 2 and 3

Your answer

This question is about waves.

The period of a progressive wave can be determined from Fig. 16.1. Add a correct label to

the horizontal axis so that the period can be found.

A progressive wave has wavelength , frequency f and period T.

Show that the speed v of the wave is given by the equation v = f.

Calculate the period T of the light wave.

The rays of light are in phase at the dashed line X.

Use your two answers above to state the phase difference in degrees between the light rays at Y.

Question 16 continues on page 12

A narrow beam of unpolarised light is incident at the boundary between air and glass.

Fig. 18 shows the incident ray, the reflected ray and the refracted ray at the air-glass boundary.

The refractive index of air is 1.00 and the refractive index of the glass is 1.50. The angle of incidence of the light is 56.3°.

Show that the angle between the refracted ray in the glass and the reflected ray in the air is 90.0°.

Describe how you can demonstrate in the laboratory that the reflected light is plane polarised.

Calculate the time t taken for the refracted light to travel a depth of 6.0 cm of glass.