Option A — Sight and wave phenomena

A1. This question is about the eye and sight.

(a) State, by reference to human vision, what is meant by accommodation.

(b) Explain how accommodation is achieved in the human eye.

(c) The light output from two particular lamps is described as “warm-white” and as

“cold-white”. Both lamps emit the full spectrum of colours. State how the visual impression of temperature difference may be achieved.


A2. This question is about the Doppler effect.

At one point in an artery, blood cells flow along the axis of the artery with speed v, as shown.

A parallel beam of ultrasound of frequency 4.5 MHz is incident on the artery at an angle of 40°.The speed of ultrasound in the body tissues is c =1.5×103ms−1.

The ultrasound detected after reflection from the blood cells is found to be Doppler-shifted in frequency by 740 Hz.

The expression for the Doppler shift Δf of the ultrasound of frequency f may be assumed to be

Δf =(2fvcosθ ) /c

(a) For this stated expression, explain the inclusion of

  • (i) the factor of 2.
  • (ii) the factor cosθ.

(b) Determine a value for the speed of the blood cells in the artery.


A3. This question is about polarization.

(a) State what is meant by polarized light.

(b) Describe and explain how polarization may be used in stress analysis. You may draw a diagram if you wish.


Option B — Quantum physics and nuclear physics

B1. This question is about the wave nature of matter.

(a) Describe the de Broglie hypothesis.

(b) Outline an experiment to verify the de Broglie hypothesis.

(c) Show that the de Broglie wavelength of electrons accelerated from rest through a potential difference of 150 V is 1.0×10−10m.




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