A transverse wave of amplitude of and frerpuencjvr gives an intensity of at a distance from a point source. By what factor does the intensity: change if the amplitude is doubled and the distance to the source is halved? When a sound wave enters a denser InediuIn, what happens to the wave speed and wavelength? A} Wave speed: Increases; \"Wavelength: Increases B) Wave speed: Decreases; 'Wavelength: Decreases C] Wave speed: Increases; \"Wavelength: Decreases D] Wave speed: Decreases; 'Wavelength: Increases 17. A sound source is heard with an intensity of 0.20 W . mat a distance of 18.5 m away. What is the ratio of the intensity at distance of 18.5 m to the intensity at 26.5 m ? Give your answer to three significant figures. 18. What is the angle between rays and wavefronts, in degrees? Give your answer without unit. 19. A speaker is rated at 200 W and creates sound waves spherically around it. Susan stands 1 m from the speaker, Polly stands 2 m from the speaker. What is the ratio of the intensity of the sound wave recorded by Polly to the intensity of the sound wave recorded by Susan? Give your answer to two significant figures. 20. Below is a wavefront diagram for a source of radiation with period 350 ms. d S If the speed of the wave is 0.240 m . s-1, what is the value of d, in cm? Give your answer without units, to three significant figures.13. Both the pulses below are moving at 0.5 m . s-1 towards each other. All distances where there is no line shown on the graph have a zero displacement. Displacement / m -6 0 Distance / m What is the displacement from the equilibrium position at a distance of 1 m, after 4 s have passed? Give your answer in metres, to one significant figure and without a unit. 14. Unpolarised light is incident upon two polarisers, which have an angle of 0 between the planes of polarisation. If the original intensity is 300 W . m-2, and the final intensity is 62 W . m , what is the value of 0, to the nearest degree? Assume negligible change in distance from source. Give your answer without a unit. 15. The intensity of plane polarised light, at 30 to the vertical is /. After passing through an analyser at 60 to the vertical, what is the intensity measured? 16. A source emits radiation, such that the intensity is 70.0 W . m 2 at a distance of 130 m from the source. For a wave of double the amplitude, at what distance from the source will the intensity be double that of the original wave? Give your answer in metres, to three significant figures and without a unit