IGCSE Physics MCQs 13 - Light

Two beams of light are both the same colour of red. One beam is travelling through air. The other beam is travelling through water. Each beam has a different brightness.

Which quantity is the same for both sets of waves?

• Amplitude

• Frequency

• Speed

• Wavelength

The diagram shows a ray of light in air incident on a glass block. Some of the light is refracted and some of the light is reflected. Two angles, p and q, are marked on the diagram.

Which answer gives the angle of incidence (p or q) and states whether total internal reflection occurs (yes/no)?

• p, no

• p, yes

• q, no

• q, yes

The diagram shows a ray of light in glass incident on the surface between the glass and air.

What happens if the angle of incidence is made larger than the critical angle for the glass?

• The angle of refraction becomes equal to 90 degrees

• There is a refracted ray, and a ray inside the glass.

• There is a refracted ray only.

• There is only a ray reflected inside the glass.

The diagram shows how a ray of light refracts when going from air to Perspex. The critical angle of Perspex is c. Which expression is correct?

• sin x /sin z = sin c

• sin z / sin x = sin c

• sin w / sin y = sin c

• sin y / sin w = sin c

The letter F is reflected in a mirror. What does the optical image look like?

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In the diagram, the mountaineer can hear the stream although he cannot see it. When he is closer to the gully, he can both hear and see the stream. When he is further from the gully, he can neither hear nor see the stream.

Which statement is NOT correct?

• As he approaches the gully edge, he hears first the short wavelength, higher frequencies and then the long wavelength, lower frequencies.

• As he approaches the gully edge, the sound becomes louder.

• He hears the stream because some of the sound is diffracted.

• He hears the stream because some of the sound is reflected from the opposite wall of the gully.

Which diagram shows what happens when a ray of white light passes through a prism?

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Light travels in a vacuum and then enters a glass block. The speed of the light in the glass block is 2.0 x 10^8 m/s.

Which statement about the speed of light is correct?

• The speed in a vacuum is 1.5 times the speed in the glass.

• The speed in the glass is the same as the speed in a vacuum.

• The speed in the glass is 1.5 times the speed in a vacuum.

• The speed in the glass is 1.0 x 10^8 times the speed in a vacuum.