What is the speed of light in air?

1.   ?    300 m/s
2.   ?    3 million m/s
3.   ?    30 million m/s
4.   ?    300 million m/s

When a light ray passes from air into a glass block at an angle,

1.   ?    its path is undeviated.
2.   ?    it bends away from the normal line
3.   ?    it bends towards the normal line
4.   ?    it undergoes total internal reflection

Which one of these statements about refraction of different coloured lights is correct?

1.   ?    All colours are refracted by the same amount.
2.   ?    Red light is refracted less than blue light.
3.   ?    Red light is refracted more than blue light.
4.   ?    Refraction only occurs with white light. Coloured light is not refracted at all.

Which one of these statements is correct about the refractive index, n of a material?

1.   ?    n = speed of light in air x speed in the material. The units are metres squared per second squared.
2.   ?    n = speed of light in material ÷ speed in air. There are no units.
3.   ?    n = speed of light in air ÷ speed in the material. The units are seconds per metre.
4.   ?    n = speed of light in air ÷ speed in the material. There are no units.

Which one of these statements is true about how we measure angles of light rays?

1.   ?    The incoming ray is called the incident ray. The angle of incidence is measured from the normal.
2.   ?    The incoming ray is called the emergent ray. The angle of incidence is measured from the normal.
3.   ?    The incoming ray is called the incident ray. The angle of incidence is measured from the boundary.
4.   ?    The incoming ray is called the emergent ray. The angle of incidence is measured from the boundary.

Light passes from a material of refractive index n1 at an incident angle of X and is refracted into material of refractive index n2 an angle of refraction Y. Which one of these is the correct equation to use?

1.   ?    n1n2 = (sinX) × (sinY)
2.   ?    n1 ÷ sin X = n2 ÷ sin Y
3.   ?    n1 sinX = n2 sinY
4.   ?    n1 sin Y = n2 sin X

Which one of these statement best describes the critical angle?

1.   ?    Then angle below which total internal reflection occurs.
2.   ?    The angle at which the angle of refraction is 90 degrees.
3.   ?    The only angle at which total internal reflection occurs.
4.   ?    The angle at which the angle of incidence is 90 degrees.

The critical angle Xc and the refractive index n can be related by:

1.   ?    sin Xc = 1/n
2.   ?    n = sin Xc
3.   ?    Xc = 1/n
4.   ?    n = Xc

Which one of these is a use of total internal reflection?

1.   ?    A lens focussing a beam of light.
2.   ?    An image seen in a mirror.
3.   ?    A prism splitting white light into the colours of the rainbow.
4.   ?    A prism used in a periscope.

Which one of these statements is true about optical fibres?

1.   ?    Light is passes through by total internal reflection. There is cladding of material of lower refractive index, but this can degrade the performance.
2.   ?    Light is passes through by total internal reflection. There is cladding of material of lower refractive index.
3.   ?    Light is passes through by total internal reflection. There is cladding of material of higher refractive index.
4.   ?    Light is passes through as a series of compressions and rarefactions. There is cladding of material of lower refractive index.