Superposition, Stationary Waves and Beats MCQs

Question 1

An organ stop called 'voix céleste' deliberately uses two pipes slightly out of tune to produce:

Accepted Answer

a pleasant wavering (beats) effect

Answer

silence

Answer

a higher octave

Answer

an echo

Question 2

Nodes in a stationary wave are 12 cm apart and the frequency is 50 Hz. The speed of the travelling waves is:

Accepted Answer

12 m/s

Answer

6 m/s

Answer

24 m/s

Answer

600 m/s

Question 3

Two loudspeakers connected to the same signal generator are:

Accepted Answer

coherent sources

Answer

incoherent sources

Answer

sources of light

Answer

unable to interfere

Question 4

The time between two successive loud sounds in beats of 4 Hz is:

Accepted Answer

0.25 s

Answer

2 s

Answer

4 s

Answer

0.5 s

Question 5

For constructive interference from in-phase sources, the path difference is:

Accepted Answer

nlambda

Answer

lambda4

Answer

(n + tfrac12)lambda

Question 6

A string of length 0.9 m fixed at both ends vibrates in 2 loops. The wavelength is:

Accepted Answer

0.9 m

Answer

0.45 m

Answer

1.0 m

Answer

1.8 m

Question 7

In the microwave experiment, a stationary wave is formed by:

Accepted Answer

microwaves reflected from a metal plate overlapping the incident waves

Answer

microwaves passing through glass

Answer

microwaves absorbed by water

Answer

two different transmitters

Question 8

A diffraction grating produces sharp bright lines because of:

Accepted Answer

diffraction combined with interference from many slits

Answer

reflection only

Answer

the Doppler effect

Answer

polarization

Question 9

If the length of a vibrating string is halved (same tension), its fundamental frequency:

Accepted Answer

doubles

Answer

quadruples

Answer

halves

Answer

stays the same

Question 10

Dark fringes in Young's double-slit experiment are due to:

Accepted Answer

destructive interference

Answer

diffraction only

Answer

constructive interference

Answer

absorption

Question 11

Small paper riders placed on a vibrating string fall off at the:

Accepted Answer

antinodes

Answer

ends

Answer

centre only

Answer

nodes

Question 12

Beats are produced because the two waves:

Accepted Answer

drift in and out of phase

Answer

are polarized

Answer

travel in opposite directions

Answer

have different speeds

Question 13

A violinist tunes the A string against a 440 Hz reference and hears no beats. The A string frequency is:

Accepted Answer

440 Hz

Answer

880 Hz

Answer

439 Hz

Answer

441 Hz

Question 14

A string produces 5 beats/s with a 256 Hz fork. Loosening the string slightly gives 7 beats/s. The original frequency of the string was:

Accepted Answer

251 Hz

Answer

256 Hz

Answer

263 Hz

Answer

261 Hz

Question 15

Passive noise reduction (as opposed to active cancellation) uses:

Accepted Answer

sound-absorbing padding

Answer

anti-noise waves

Answer

polarizers

Answer

radio waves

Question 16

At a point, one wave alone gives a displacement of 2.5 cm and another alone gives 1.5 cm. When both arrive, the displacement is:

Accepted Answer

4 cm

Answer

3.75 cm

Answer

2.92 cm

Answer

1 cm

Question 17

Water waves from two dippers attached to the same vibrating bar are:

Accepted Answer

coherent

Answer

polarized

Answer

longitudinal

Answer

incoherent

Question 18

Noise-cancelling headphones are an application of:

Accepted Answer

the principle of superposition

Answer

polarization

Answer

the Doppler effect

Answer

total internal reflection

Question 19

For the same string (length 1 m, wave speed 100 m/s), the frequency of the third harmonic is:

Accepted Answer

150 Hz

Answer

200 Hz

Answer

50 Hz

Answer

100 Hz

Question 20

Musicians tune their instruments using beats by:

Accepted Answer

adjusting until the beats slow down and disappear

Answer

playing louder

Answer

ignoring the beats

Answer

making the beats faster

Question 21

For destructive interference, the phase difference is:

Accepted Answer

pi, 3pi, 5pi, ldots

Answer

0, 2pi, 4pi, ldots

Answer

pi2

Answer

2pi

Question 22

Each piano key in the middle range has two or three strings. A 'chorus' or 'wavering' sound occurs when:

Accepted Answer

these strings are slightly out of tune, producing beats

Answer

the key is not pressed

Answer

they are perfectly in tune

Answer

the piano is in a vacuum

Question 23

Diffraction does NOT change:

Accepted Answer

the frequency of the waves

Answer

the shape of the wavefronts

Answer

the direction of the waves

Answer

the region the waves reach

Question 24

A laser is a good source for interference experiments because its light is:

Accepted Answer

highly coherent and monochromatic

Answer

polarized only

Answer

longitudinal

Answer

very hot

Question 25

If the phase difference between two sources changes randomly, the interference pattern:

Accepted Answer

changes so fast that no steady pattern is seen

Answer

becomes brighter

Answer

is unaffected

Answer

becomes sharper

Superposition, Stationary Waves and Beats MCQs — Physics

1. An organ stop called 'voix céleste' deliberately uses two pipes slightly out of tune to produce:

2. Nodes in a stationary wave are 12 cm apart and the frequency is 50 Hz. The speed of the travelling waves is:

3. Two loudspeakers connected to the same signal generator are:

4. The time between two successive loud sounds in beats of 4 Hz is:

5. For constructive interference from in-phase sources, the path difference is:

6. A string of length 0.9 m fixed at both ends vibrates in 2 loops. The wavelength is:

7. In the microwave experiment, a stationary wave is formed by:

8. A diffraction grating produces sharp bright lines because of:

9. If the length of a vibrating string is halved (same tension), its fundamental frequency:

10. Dark fringes in Young's double-slit experiment are due to:

11. Small paper riders placed on a vibrating string fall off at the:

12. Beats are produced because the two waves:

13. A violinist tunes the A string against a 440 Hz reference and hears no beats. The A string frequency is:

14. A string produces 5 beats/s with a 256 Hz fork. Loosening the string slightly gives 7 beats/s. The original frequency of the string was:

15. Passive noise reduction (as opposed to active cancellation) uses:

16. At a point, one wave alone gives a displacement of 2.5 cm and another alone gives 1.5 cm. When both arrive, the displacement is:

17. Water waves from two dippers attached to the same vibrating bar are:

18. Noise-cancelling headphones are an application of:

19. For the same string (length 1 m, wave speed 100 m/s), the frequency of the third harmonic is:

20. Musicians tune their instruments using beats by:

21. For destructive interference, the phase difference is:

22. Each piano key in the middle range has two or three strings. A 'chorus' or 'wavering' sound occurs when:

23. Diffraction does NOT change:

24. A laser is a good source for interference experiments because its light is:

25. If the phase difference between two sources changes randomly, the interference pattern:

More Physics chapters