Question 18M.2.HL.TZ2.b.i
| Date | May 2018 | Marks available | [Maximum mark: 2] | Reference code | 18M.2.HL.TZ2.b.i |
| Level | HL | Paper | 2 | Time zone | TZ2 |
| Command term | Determine | Question number | b.i | Adapted from | N/A |
A loudspeaker emits sound towards the open end of a pipe. The other end is closed. A standing wave is formed in the pipe. The diagram represents the displacement of molecules of air in the pipe at an instant of time.
The loudspeaker in (a) now emits sound towards an air–water boundary. A, B and C are parallel wavefronts emitted by the loudspeaker. The parts of wavefronts A and B in water are not shown. Wavefront C has not yet entered the water.
The speed of sound in air is 340 m s–1 and in water it is 1500 m s–1.
The wavefronts make an angle θ with the surface of the water. Determine the maximum angle, θmax, at which the sound can enter water. Give your answer to the correct number of significant figures.
[2]
θc = 13«°»
Award [2] for a bald correct answer
Award [2] for a bald answer of 13.1
Answer must be to 2/3 significant figures to award MP2
Allow 0.23 radians
[2 marks]
