Superposition, Stationary Waves and Beats MCQs

Question 1

A tuning fork of 400 Hz and an unknown fork give 3 beats/s. The unknown frequency is:

Accepted Answer

397 Hz or 403 Hz

Answer

1200 Hz

Answer

133 Hz

Answer

exactly 403 Hz

Question 2

A node in a stationary wave is a point of:

Accepted Answer

zero amplitude (no displacement)

Answer

maximum amplitude

Answer

maximum speed

Answer

maximum energy flow

Question 3

Destructive interference occurs when two waves meet:

Accepted Answer

in antiphase (crest on trough)

Answer

at the same speed only

Answer

with zero amplitude

Answer

in phase

Question 4

A sound wave and its exact inverted copy add to give:

Accepted Answer

zero displacement everywhere

Answer

a wave of double frequency

Answer

a stationary wave

Answer

double displacement

Question 5

We can hear people round a corner but cannot see them because:

Accepted Answer

sound wavelengths are similar to doorway sizes but light wavelengths are tiny

Answer

light cannot travel round corners at all

Answer

sound travels faster than light

Answer

sound is transverse

Question 6

Two tuning forks of 100 Hz and 102 Hz are sounded together. The number of beats heard per second is:

Accepted Answer

1.5

Answer

3

Answer

101

Answer

202

Question 7

A pipe closed at one end produces only:

Accepted Answer

odd harmonics (1 : 3 : 5 …)

Answer

even harmonics

Answer

the fundamental only

Answer

all harmonics

Question 8

A progressive wave differs from a stationary wave because in a progressive wave:

Accepted Answer

all points have the same amplitude and energy is transferred

Answer

no energy is transferred

Answer

there are nodes and antinodes

Answer

the wave does not move

Question 9

In a region of destructive interference, the wave energy:

Accepted Answer

is redistributed to regions of constructive interference

Answer

is destroyed

Answer

is created elsewhere

Answer

turns into heat only

Question 10

Why don't noise-cancelling headphones cancel the music you're listening to?

Accepted Answer

the circuit only generates anti-noise for the outside sound picked up by the microphone

Answer

the music is polarized

Answer

music is a different kind of wave

Answer

music travels faster

Question 11

Two separate light bulbs do not produce a visible interference pattern because they are:

Accepted Answer

not coherent

Answer

polarized

Answer

too far apart

Answer

too bright

Question 12

Diffraction of waves provides evidence that light is:

Accepted Answer

a wave

Answer

longitudinal

Answer

a particle only

Answer

a sound wave

Question 13

A piano tuner tightens a string while sounding it with a 440 Hz fork. The beats slow from 4 Hz to 2 Hz. The string's frequency is now:

Accepted Answer

438 Hz or 442 Hz

Answer

444 Hz only

Answer

880 Hz

Answer

exactly 440 Hz

Question 14

Which condition is needed for a stable interference pattern?

Accepted Answer

the sources must be coherent

Answer

the sources must be very bright

Answer

the waves must be longitudinal

Answer

the sources must be different colours

Question 15

A string of length 0.5 m fixed at both ends carries waves at 200 m/s. Its fundamental frequency is:

Accepted Answer

200 Hz

Answer

800 Hz

Answer

400 Hz

Answer

100 Hz

Question 16

Two tuning forks of 330 Hz and 335 Hz are sounded together. The number of beats heard per second is:

Accepted Answer

5

Answer

665

Answer

332

Answer

10

Question 17

Two coherent waves of amplitudes 4 mm and 4 mm meet. The maximum and minimum possible resultant amplitudes are:

Accepted Answer

8 mm and 0 mm

Answer

8 mm and 4 mm

Answer

16 mm and 0 mm

Answer

4 mm and 4 mm

Question 18

Beats are an example of interference in:

Accepted Answer

time (at one place)

Answer

space only

Answer

polarization

Answer

diffraction

Question 19

For constructive interference, the phase difference is:

Accepted Answer

0, 2pi, 4pi, ldots

Answer

any value

Answer

pi2

Answer

pi, 3pi, 5pi, ldots

Question 20

Two coherent sources in phase emit waves of wavelength lambda. At a point, the path difference is 0.5lambda. The interference there is:

Accepted Answer

destructive

Answer

neither — there is no interference

Answer

constructive

Answer

constructive only for sound

Question 21

Two coherent sources in phase emit waves of wavelength lambda. At a point, the path difference is 2lambda. The interference there is:

Accepted Answer

constructive

Answer

constructive only for sound

Answer

neither — there is no interference

Answer

destructive

Question 22

For the second harmonic of a string, the number of loops is:

Accepted Answer

2

Answer

1

Answer

3

Answer

4

Question 23

Noise-cancelling headphones need a battery because:

Accepted Answer

electronic circuits must process the noise and drive the speakers

Answer

they use magnets only

Answer

the sound waves need charging

Answer

they heat the ear

Question 24

Walking past two loudspeakers playing the same note, you hear:

Accepted Answer

alternate loud and quiet regions

Answer

a constant loudness

Answer

silence everywhere

Answer

a changing pitch

Question 25

Microwaves from one transmitter passing through two slits act as:

Accepted Answer

two coherent sources

Answer

two incoherent sources

Answer

longitudinal waves

Answer

one incoherent source

Superposition, Stationary Waves and Beats MCQs — Physics (page 5)

101. A tuning fork of 400 Hz and an unknown fork give 3 beats/s. The unknown frequency is:

102. A node in a stationary wave is a point of:

103. Destructive interference occurs when two waves meet:

104. A sound wave and its exact inverted copy add to give:

105. We can hear people round a corner but cannot see them because:

106. Two tuning forks of 100 Hz and 102 Hz are sounded together. The number of beats heard per second is:

107. A pipe closed at one end produces only:

108. A progressive wave differs from a stationary wave because in a progressive wave:

109. In a region of destructive interference, the wave energy:

110. Why don't noise-cancelling headphones cancel the music you're listening to?

111. Two separate light bulbs do not produce a visible interference pattern because they are:

112. Diffraction of waves provides evidence that light is:

113. A piano tuner tightens a string while sounding it with a 440 Hz fork. The beats slow from 4 Hz to 2 Hz. The string's frequency is now:

114. Which condition is needed for a stable interference pattern?

115. A string of length 0.5 m fixed at both ends carries waves at 200 m/s. Its fundamental frequency is:

116. Two tuning forks of 330 Hz and 335 Hz are sounded together. The number of beats heard per second is:

117. Two coherent waves of amplitudes 4 mm and 4 mm meet. The maximum and minimum possible resultant amplitudes are:

118. Beats are an example of interference in:

119. For constructive interference, the phase difference is:

120. Two coherent sources in phase emit waves of wavelength lambda. At a point, the path difference is 0.5lambda. The interference there is:

121. Two coherent sources in phase emit waves of wavelength lambda. At a point, the path difference is 2lambda. The interference there is:

122. For the second harmonic of a string, the number of loops is:

123. Noise-cancelling headphones need a battery because:

124. Walking past two loudspeakers playing the same note, you hear:

125. Microwaves from one transmitter passing through two slits act as:

More Physics chapters