Chapter 12 Sound

Answer sheet

1. Sound waves travel at greater speed in water than in air. When a sound wave passes from water into air, its
[A] frequency increases, while the wavelength remains unchanged.
[B] frequency decreases while the wavelength remains unchanged.
[C] frequency remains unchanged while the wavelength increases.
[D] frequency remains unchanged while the wavelength decreases.

2.Considering sound waves, microwaves, and X-rays, diffraction can be observed in principle
[A] only with X-rays, but not with microwaves and sound waves.
[B] with X-rays and microwaves, but not with sound waves.
[C] with microwaves and sound waves, but not with X-rays.
[D] with all of them.

3. Sound waves are classified as longitudinal because
[A] they always originate from a vibrating source.
[B] they require a material medium through which to pass.
[C] the pressure variations and the particle displacements are out of phase.
[D] the particle displacements take place along the line of propagation of the waves.

4. A ship 1200 m distant from a large cliff sounds a short note of 222 vib/sec on its foghorn. The speed of the sound is 330 m/sec., the time required for the sound to reach the cliff is, approximately,
[A] less than 0.1 sec
[B] 0.3 sec
[C] 1.8 sec
[D] 3.6 sec
[E] 7.2 sec