1. This question is about the eye.
(a) Explain, with reference to spectral response, why the eye has poor colour sensitivity under scotopic vision.
(b) Outline how the distribution of retinal cells in the eye accounts for differences in perception.
2. This question is about sound waves.
A whistle on a steam train consists of a pipe that is open at one end and closed at the other.The sounding length of the whistle is 0.27 m and the steam pressure in the whistle is so great that the third harmonic of the pipe is sounding. The speed of sound in air is 340ms–1.
(a) (i) Show that there must be a node at a distance of 0.18 m from the closed end of the pipe.
(ii) Calculate the frequency of the whistle sound.
(b) The train is moving directly away from a stationary observer at a speed of 22ms–1 while the whistle is sounding. Calculate the frequency heard by the observer.
3. This question is about diffraction and resolution.
Monochromatic light is incident normally on a single narrow slit and gives rise to a diffraction pattern on a screen.
(a) Sketch, for the diffraction pattern produced, a graph showing the variation of the relative intensity of the light with the angle measured from the centre of the slit.
(b) The single narrow slit is replaced by a double narrow slit. Explain, with reference to your answer to (a), how the Rayleigh criterion applies to the diffraction patterns produced by the light emerging from the two slits.
(c) Two lamps emit light of wavelength 620 nm. The lights are observed through a circular aperture of diameter 1.5 mm from a distance of 850 m. Calculate the minimum distance between the lamps so that they are resolved.
4. This question is about polarization.
Mathematical calculators often use a liquid-crystal display (LCD). Outline how you would demonstrate that the display emits plane polarized light.