A1. This question is about the functioning of the human eye.
(a) Outline the differences between the functions performed by rod and cone cells in the human eye.
(b) The sketch graph shows how the relative sensitivity S of the cone cells in a human eye varies with the wavelength λ of the incident radiation. On the same axes, sketch the corresponding curve for rod cells.
(c) State the effect on the appearance of a red object when it is illuminated with red light only and blue light only.
A2. This question is about the Doppler effect in sound.
(a) A fire engine is travelling at a constant velocity towards a stationary observer. Its siren emits a note of constant frequency. As the engine passes close to the observer, the frequency of the note perceived by the observer decreases. Explain this decrease in terms of the wavefronts of the note emitted by the siren.
(b) The frequency of the note emitted by the siren is 400 Hz. After the fire engine has passed,the frequency of the note detected by the observer is 360 Hz. Calculate the speed of the fire engine. (Take the speed of sound in air to be 340 ms–1.)
A3. This question is about polarized light.
(a) Describe what is meant by polarized light.
(b) (i) State Brewster’s law.
(ii) When light is incident on a plastic surface the angle between the reflected and refracted ray is 90°. The angle of incidence is 56°. Calculate the refractive index of the plastic.
A4. This question is about resolution.
A car is travelling along a straight road at night. To a distant observer the two headlamps of the car appear as a single point source. With the aid of an appropriately labelled sketch graph, explain this observation.