1. This question is about the eye and its resolution.
A house on a hillside is viewed at night by a human eye.
(a) Distinguish, with reference to cells in the retina and their properties, between the image viewed at night time and that seen during the day. 
(b) The eye viewing the house has a pupil of diameter 2.5 mm. Two lamps on the wall of the house are separated by a horizontal distance of 1.5 m and produce light of average wavelength 450 nm. The eye can just resolve the images of the two lamps. Determine the distance between the house and the eye.
2. This question is about standing (stationary) waves.The diagram shows an arrangement used to produce a standing (stationary) wave on a stretched string of length 2.4 m. A standing wave with five loops appears when the frequency of the oscillator is set to 150 Hz, as shown below.
(a) State the name given to point X on the string.
(b) (i) Calculate the speed of the wave along the string.
(ii) Calculate the frequency of the oscillator that would produce a standing wave with two loops on this string.
3. This question is about the Doppler effect.
The diagram shows wavefronts in air produced by a stationary source S of sound.The distance between successive wavefronts is equal to the wavelength of the sound.The speed of sound is c.
(a) On the diagram, sketch three successive wavefronts produced when S is moving to the left at a speed of 0.5c.
(b) A source of X-rays rotates on a turntable. Radiation of wavelength 7.5 nm is emitted by the source and undergoes a maximum shift of 0.50 fm. The distance between the source and the detector is large in comparison to the diameter of the turntable.
(i) Determine the speed of a point on the edge of the turntable.
(ii) State the assumption you made in your answer to (b)(i).
4. This question is about polarized light.
An analyser is used with polarized light.
(a) Outline the function of an analyser in this context.
(b) Polarized light of intensity I0 is incident on the analyser.
(i) The transmission axis of the analyser is at an angle of 25˚ to the electric field of the polarized light. Calculate, in terms of I0, the intensity of the light that leaves the analyser.
(ii) The angle θ between the transmission axis of the analyser and the electric fi eld of the polarized light is varied. On the axes, sketch a graph to show the variation with θ of the intensity of the light leaving the analyser.