Superposition, Stationary Waves and Beats MCQs

Question 1

A guitarist plays the same note on two strings and hears 2 beats per second. This means:

Accepted Answer

the strings are 2 Hz out of tune

Answer

the strings are perfectly tuned

Answer

one string is broken

Answer

the strings are an octave apart

Question 2

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

Accepted Answer

(n + tfrac12)lambda

Answer

lambdan

Answer

2nlambda

Answer

nlambda

Question 3

For effective cancellation, the delay in generating anti-noise must be:

Accepted Answer

very small compared with the period of the noise

Answer

exactly one second

Answer

unimportant

Answer

much longer than the period

Question 4

When an orchestra tunes before a concert, the oboe plays a reference A so that other players can:

Accepted Answer

eliminate beats with it

Answer

play louder

Answer

change the speed of sound

Answer

make faster beats

Question 5

The beat frequency equals:

Accepted Answer

the difference between the two frequencies

Answer

the average of the frequencies

Answer

the sum of the two frequencies

Answer

the product of the frequencies

Question 6

Superposition applies to:

Accepted Answer

all types of waves

Answer

only water waves

Answer

only sound waves

Answer

only light waves

Question 7

For the same string (length 0.8 m, wave speed 320 m/s), the frequency of the third harmonic is:

Accepted Answer

600 Hz

Answer

800 Hz

Answer

400 Hz

Answer

200 Hz

Question 8

Monochromatic means:

Accepted Answer

of a single frequency (wavelength)

Answer

of a single amplitude

Answer

of one polarization

Answer

of one direction

Question 9

A string of length 2 m fixed at both ends vibrates in 4 loops. The wavelength is:

Accepted Answer

1 m

Answer

0.5 m

Answer

2 m

Answer

8 m

Question 10

The microphone in noise-cancelling headphones is used to:

Accepted Answer

detect the incoming noise so an opposite wave can be generated

Answer

record music

Answer

measure temperature

Answer

amplify the noise

Question 11

Active noise control is also used in:

Accepted Answer

aircraft cabins and car interiors

Answer

X-ray machines

Answer

microwave ovens

Answer

telescopes

Question 12

For interference, the waves from coherent sources should also have:

Accepted Answer

similar amplitudes, for clear minima

Answer

different speeds

Answer

different wavelengths

Answer

very different amplitudes

Question 13

A tuning fork of 425 Hz resonates with a closed air column of length 20 cm (first resonance). The speed of sound is:

Accepted Answer

340 m/s

Answer

170 m/s

Answer

680 m/s

Answer

85 m/s

Question 14

For the same string (length 0.5 m, wave speed 200 m/s), the frequency of the third harmonic is:

Accepted Answer

600 Hz

Answer

200 Hz

Answer

800 Hz

Answer

400 Hz

Question 15

The fundamental (first harmonic) of a string fixed at both ends has:

Accepted Answer

one loop, with nodes at the ends

Answer

an antinode at each end

Answer

two loops

Answer

no nodes

Question 16

Diffraction is most noticeable when the gap width is:

Accepted Answer

about the same as the wavelength

Answer

zero

Answer

much larger than the wavelength

Answer

infinitely large

Question 17

The principle of superposition states that when two waves meet, the resultant displacement is:

Accepted Answer

the vector sum of the individual displacements

Answer

the product of the displacements

Answer

the larger of the two displacements

Answer

always zero

Question 18

Two flutes play notes of 523 Hz and 527 Hz. The listener hears:

Accepted Answer

4 beats per second at a pitch of about 525 Hz

Answer

two separate notes

Answer

1050 Hz

Answer

8 beats per second

Question 19

A pipe of length 0.34 m is closed at one end (v = 340 m/s, end correction ignored). Its fundamental frequency is:

Accepted Answer

250 Hz

Answer

500 Hz

Answer

125 Hz

Answer

750 Hz

Question 20

For a tube closed at one end, the first resonance occurs when the length is:

Accepted Answer

lambda4

Answer

lambda2

Answer

2lambda

Answer

lambda

Question 21

A stationary (standing) wave is formed when:

Accepted Answer

two waves of the same frequency and amplitude travel in opposite directions and superpose

Answer

one wave is reflected and absorbed

Answer

a wave stops moving

Answer

two waves of different frequencies meet

Question 22

In the tuning above, tightening slowed the beats, so the string's frequency was originally:

Accepted Answer

436 Hz (below 440 Hz)

Answer

448 Hz

Answer

440 Hz

Answer

444 Hz

Question 23

At a point, one wave alone gives a displacement of -2 cm and another alone gives -3 cm. When both arrive, the displacement is:

Accepted Answer

-5 cm

Answer

3.61 cm

Answer

6 cm

Answer

1 cm

Question 24

A tabla player tightens the drum skin to remove beats with the harmonium. Tightening:

Accepted Answer

raises the drum's pitch

Answer

lowers the pitch

Answer

changes the speed of sound

Answer

has no effect

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 (page 2)

26. A guitarist plays the same note on two strings and hears 2 beats per second. This means:

27. For destructive interference from in-phase sources, the path difference is:

28. For effective cancellation, the delay in generating anti-noise must be:

29. When an orchestra tunes before a concert, the oboe plays a reference A so that other players can:

30. The beat frequency equals:

31. Superposition applies to:

32. For the same string (length 0.8 m, wave speed 320 m/s), the frequency of the third harmonic is:

33. Monochromatic means:

34. A string of length 2 m fixed at both ends vibrates in 4 loops. The wavelength is:

35. The microphone in noise-cancelling headphones is used to:

36. Active noise control is also used in:

37. For interference, the waves from coherent sources should also have:

38. A tuning fork of 425 Hz resonates with a closed air column of length 20 cm (first resonance). The speed of sound is:

39. For the same string (length 0.5 m, wave speed 200 m/s), the frequency of the third harmonic is:

40. The fundamental (first harmonic) of a string fixed at both ends has:

41. Diffraction is most noticeable when the gap width is:

42. The principle of superposition states that when two waves meet, the resultant displacement is:

43. Two flutes play notes of 523 Hz and 527 Hz. The listener hears:

44. A pipe of length 0.34 m is closed at one end (v = 340 m/s, end correction ignored). Its fundamental frequency is:

45. For a tube closed at one end, the first resonance occurs when the length is:

46. A stationary (standing) wave is formed when:

47. In the tuning above, tightening slowed the beats, so the string's frequency was originally:

48. At a point, one wave alone gives a displacement of -2 cm and another alone gives -3 cm. When both arrive, the displacement is:

49. A tabla player tightens the drum skin to remove beats with the harmonium. Tightening:

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

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