IGCSE Physics MCQs 12 - Sound

What is ultrasound?

• sound waves that are so loud that they damage human hearing

• sound waves that are too high-pitched for humans to hear

• sound waves that are too low-pitched for humans to hear

• sound waves that are too quiet for humans to hear

In the diagram, the mountaineer can hear the stream although he cannot see it. When he is closer to the gully, he can both hear and see the stream. When he is further from the gully, he can neither hear nor see the stream.

Which statement is NOT correct?

• As he approaches the gully edge, the sound becomes louder.

• As he approaches the gully edge, he hears first the short wavelength, higher frequencies and then the long wavelength, lower frequencies.

• He hears the stream because some of the sound is diffracted.

• He hears the stream because some of the sound is reflected from the opposite wall of the gully.

The diagrams show examples of wave motion. Which waves are longitudinal?

• 1 only

• 2 and 3 only

• 2, 3, and 4

• 2, and 4 only

The diagram shows compressions and rarefactions in air as a sound wave moves from left to right. A quieter sound of the same frequency is made.

What will happen to the number of particles in a region of rarefaction and in a region of compression?

• Rarefaction: Decrease | Compression: Decrease

• Rarefaction: Decrease | Compression: Increase

• Rarefaction: Increase | Compression: Decrease

• Rarefaction: Increase | Compression: Increase

A fire alarm is not loud enough and the pitch is too low. An engineer adjusts the alarm so that it produces a louder note of a higher pitch.

What effect does this have on the amplitude A and on the frequency F of the sound?

• A: larger | F: greater

• A: larger | F: smaller

• A: smaller | F: greater

• A: smaller | F: smaller