Option A — Sight and wave phenomena

A1. This question is about colour vision.

(a) State which type of receptor cell in the eye is responsible for detection of colour.

(b) The graph below shows how absorption varies with wavelength for the three types of colour receptor.

(i) Identify the colours that the receptors are sensitive to.

Receptor A:

Receptor B:

Receptor C:

(ii) Red-green colour blindness is more common than red-blue colour blindness.Using the information on the graph suggest why this is the case.

(iii) State which of the receptors absorb yellow light.


A2. This question is about standing waves on strings.

(a) A string is fixed at one end and the other free end is moved up and down. Explain how a standing wave can be formed on the string.

(b) The diagram shows a string vibrating in its fundamental (first harmonic) mode. Both ends of the string are fixed.

(i) Label an antinode on the diagram.

(ii) The length of the string is 0.85 m and its fundamental frequency is 73 Hz. Calculate the speed of the waves on the string.

(iii) Sketch how the string will appear if it is vibrated at a frequency three times that of the fundamental frequency.

(iv) State the speed of the wave when the string is vibrated at a frequency three times that of the fundamental frequency.


A3. This question is about the Doppler effect.

(a) Describe the Doppler effect.

(b) A spectral line from a source on Earth has a frequency of 4.672×1014 Hz. When this same line is observed from a distant galaxy it is found to have shifted to 4.669×1014 Hz.

(i) State the direction of the motion of the galaxy relative to Earth.




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