MCQ Questions

Question No. 1

State the three characteristics of sound and the factor on which each depends.

Answer :

Question No. 2

Explain resonance as applied to sound.

Answer :

Question No. 3

The speed of sound in aluminium is 6400 m/s and that in air is 330 m/s. One end of a 200 m long aluminium pipe is tapped with a hammer. If you place your ear at the other end of the pipe, you will hear two sounds, one in the pipe and the other in the air. What will be the difference in the time between the two sounds?

Answer :

Question No. 4

The frequency of a tuning fork is determined by striking the tuning fork and then holding it near the open end of a glass tube partly submerged in water. The smallest value of L for which a loud resonant sound is heard from the tube is 16.7 cm. Take the speed of sound in air to be 343 m/s and ignore end-corrections.

Answer :

a) Determine the frequency of the tuning fork.

b) Determine the length L for which second resonance occurs in the glass tube.

c) Draw the waveform of the standing wave in the tube for second resonance. Mark the displacement nodes and antinodes.

Question No. 5

A pipe is open at both ends and resonates at its fundamental frequency of 260 Hz. Determine the fundamental frequency if one end of the pipe is closed and the pipe is made to resonate again.

Answer :

Question No. 6

A small loudspeaker having a frequency of 1020 Hz is positioned some metres away from a wall made of hardboard. Stationary or standing waves are created in the air between the loudspeaker and the wall. Starting from the wall, four successive nodes are observed between the wall and the loudspeaker. If the speed of sound in the air is 340 m/s, calculate:

Answer :

a) the wavelength of the sound waves

b) the distance between the loudspeaker and the wall.

Question No. 7

The second overtone of an organ pipe which is open at both ends is 300 Hz. Take the speed of sound to be 340 m/s.

Answer :

a) Draw a diagram to show the stationary sound wave in the pipe. Indicate the displacement nodes and antinodes.

b) Determine the length of the pipe.

Question No. 8

The frequency of the note from a string which is fixed at both ends and vibrating in its fundamental mode is 600 Hz. Determine the frequency of the first overtone of the string and draw a sketch to illustrate the waveform of this overtone.

Answer :

Question No. 9

The diagram shows a sonometer with paper riders on its wire. The distance between the two bridges X and Y is 90 cm. When the wire is set into resonance, a standing wave is set up between X and Y in it and the paper riders at B, D and F fall off the wire.

Answer :

a) Draw a sketch to show the standing wave in the wire.

b) Determine the frequency and wavelength of the standing wave in the wire, if its fundamental frequency is 300 Hz.

c) If the speed of the surrounding air is 330 m/s, what is the frequency and wavelength of the sound wave produced in the air by the vibrating string?

Question No. 10

The sound carried by air from a guitar to a listener is a:

Answer :

longitudinal standing wave

transverse standing wave

longitudinal travelling wave

transverse travelling wave

Question No. 11

A certain sound is twice as loud as a second sound. This implies that the first sound has twice the:

Answer :

speed of the second sound

wavelength of the second sound

pitch of the second sound

amplitude of the second sound

Question No. 12

A teacher is talking to his class about sound. The sound of his voice is most likely to have a wavelength of around:

Answer :

10 m

1 m

1 × 10⁻² m

1 × 10⁻³ m

Question No. 13

Sound is transmitted in air, water and steel. Which one of the following shows the correct order of increasing speed of sound?

Answer :

air (0 °C), air (20 °C), water, steel

air (20 °C), air (0 °C), water, steel

air (20 °C), air (0 °C), steel, water

steel, water, air (20 °C), air (0 °C)

Question No. 14

A sound wave travelling through air has regions where the pressure changes are minimal (negative and maximum). These regions are called:

Answer :

compressions

rarefactions

nodes

antinodes

Question No. 15

The vibration with the largest wavelength that can be produced on a string fixed at both ends is the:

Answer :

first harmonic

first overtone

fifth harmonic

fifth overtone

Question No. 16

Which one of the following graphs represents a noise?

Answer :

Graph A

Graph B

Graph C

Graph D

Question No. 17

The quality of a note depends on its:

Answer :

wavelength

amplitude

frequency

overtones

Question No. 18

Which one of the following waveforms corresponds to a low pitched and high volume sound?

Answer :

A

B

C

D

Question No. 19

The air in a tube which is open at both ends is resonating at a frequency of 512 Hz in its fundamental mode. If the speed of sound is 330 m/s, the length of the tube is approximately:

Answer :

64.5 cm

32.2 cm

16.1 cm

38.8 cm

Chapter

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