Superposition, Stationary Waves and Beats MCQs

Question 1

Two coherent sources can have:

Accepted Answer

a constant non-zero phase difference

Answer

different frequencies

Answer

only zero phase difference

Answer

a random phase difference

Question 2

Two tuning forks of 440 Hz and 443 Hz are sounded together. The number of beats heard per second is:

Accepted Answer

3

Answer

442

Answer

6

Answer

883

Question 3

The phase difference between the noise and the anti-noise should be:

Accepted Answer

pi rad

Answer

pi4 rad

Answer

2pi rad

Answer

0 rad

Question 4

Particles in adjacent loops of a stationary wave vibrate:

Accepted Answer

in antiphase

Answer

with 90^circ phase difference

Answer

with no motion

Answer

in phase

Question 5

Two identical waves interfere completely destructively. The resultant amplitude is:

Accepted Answer

zero

Answer

the same as one wave

Answer

half

Answer

double

Question 6

When two sounds produce beats, the pitch heard is:

Accepted Answer

the average of the two frequencies

Answer

zero

Answer

the sum of the frequencies

Answer

the difference of the frequencies

Question 7

In the microwave experiment, the distance moved by the detector between two successive minima is 1.6 cm. The microwave frequency is (c = 3 10^8 m/s):

Accepted Answer

9.4 10^9 Hz

Answer

4.7 10^9 Hz

Answer

1.9 10^10 Hz

Answer

1.6 10^10 Hz

Question 8

Two instruments play together with 6 beats in 2 seconds. Their frequency difference is:

Accepted Answer

3 Hz

Answer

6 Hz

Answer

12 Hz

Answer

2 Hz

Question 9

Behind a small obstacle in a ripple tank, waves:

Accepted Answer

bend round into the 'shadow' region

Answer

leave a perfectly sharp shadow

Answer

speed up

Answer

reflect only

Question 10

Ordinary light from a filament lamp is incoherent because:

Accepted Answer

atoms emit light randomly and independently

Answer

it has only one frequency

Answer

it is polarized

Answer

it is very weak

Question 11

A string of length 0.8 m fixed at both ends carries waves at 320 m/s. Its fundamental frequency is:

Accepted Answer

200 Hz

Answer

800 Hz

Answer

400 Hz

Answer

100 Hz

Question 12

The coherence of a source is important in:

Accepted Answer

holography

Answer

sunbathing

Answer

photographs with flash

Answer

ordinary room lighting

Question 13

In a microwave stationary-wave experiment, adjacent nodes are 1.4 cm apart. The wavelength of the microwaves is:

Accepted Answer

2.8 cm

Answer

5.6 cm

Answer

11.2 cm

Answer

1.4 cm

Question 14

A string of length 1.2 m fixed at both ends vibrates in 3 loops. The wavelength is:

Accepted Answer

0.8 m

Answer

0.4 m

Answer

1.6 m

Answer

3.6 m

Question 15

A pipe open at both ends produces:

Accepted Answer

all harmonics (1 : 2 : 3 …)

Answer

only odd harmonics

Answer

only even harmonics

Answer

no harmonics

Question 16

In Melde's experiment (vibrating string), the stationary wave is set up by:

Accepted Answer

waves reflected from the fixed end overlapping the incident waves

Answer

two separate vibrators

Answer

wind

Answer

sound from a loudspeaker

Question 17

During diffraction, the wavelength of the waves:

Accepted Answer

stays the same

Answer

increases

Answer

decreases

Answer

becomes zero

Question 18

In the example above, sticking wax on the unknown fork (lowering its frequency) increases the beats to 5/s. The unknown frequency was:

Accepted Answer

397 Hz

Answer

405 Hz

Answer

403 Hz

Answer

395 Hz

Question 19

Destructive interference in noise-cancelling headphones means the energy of the noise is:

Accepted Answer

not destroyed — energy is redistributed or not delivered to the ear

Answer

converted into electric charge

Answer

converted into light

Answer

destroyed completely

Question 20

In a graph showing two waves travelling in opposite directions, at the instant they are exactly in phase the resultant:

Accepted Answer

has twice the amplitude of each wave at the antinodes

Answer

is zero everywhere

Answer

has the same amplitude as one wave

Answer

is a straight line

Question 21

Which waves would diffract most through a 1 m doorway?

Accepted Answer

sound of wavelength 1 m

Answer

visible light

Answer

ultraviolet

Answer

X-rays

Question 22

If the anti-noise wave were in phase with the noise, the listener would hear:

Accepted Answer

louder noise

Answer

no change

Answer

silence

Answer

a higher pitch

Question 23

A string of length 1 m fixed at both ends carries waves at 100 m/s. Its fundamental frequency is:

Accepted Answer

50 Hz

Answer

200 Hz

Answer

25 Hz

Answer

100 Hz

Question 24

When light passes through a single narrow slit, the pattern on a screen is:

Accepted Answer

a broad central bright band with weaker bands either side

Answer

a single sharp line

Answer

a uniform bright patch

Answer

complete darkness

Question 25

After two wave pulses pass through each other, they:

Accepted Answer

continue with their original shapes

Answer

reverse direction

Answer

merge into one pulse

Answer

are destroyed

Superposition, Stationary Waves and Beats MCQs — Physics (page 6)

126. Two coherent sources can have:

127. Two tuning forks of 440 Hz and 443 Hz are sounded together. The number of beats heard per second is:

128. The phase difference between the noise and the anti-noise should be:

129. Particles in adjacent loops of a stationary wave vibrate:

130. Two identical waves interfere completely destructively. The resultant amplitude is:

131. When two sounds produce beats, the pitch heard is:

132. In the microwave experiment, the distance moved by the detector between two successive minima is 1.6 cm. The microwave frequency is (c = 3 10^8 m/s):

133. Two instruments play together with 6 beats in 2 seconds. Their frequency difference is:

134. Behind a small obstacle in a ripple tank, waves:

135. Ordinary light from a filament lamp is incoherent because:

136. A string of length 0.8 m fixed at both ends carries waves at 320 m/s. Its fundamental frequency is:

137. The coherence of a source is important in:

138. In a microwave stationary-wave experiment, adjacent nodes are 1.4 cm apart. The wavelength of the microwaves is:

139. A string of length 1.2 m fixed at both ends vibrates in 3 loops. The wavelength is:

140. A pipe open at both ends produces:

141. In Melde's experiment (vibrating string), the stationary wave is set up by:

142. During diffraction, the wavelength of the waves:

143. In the example above, sticking wax on the unknown fork (lowering its frequency) increases the beats to 5/s. The unknown frequency was:

144. Destructive interference in noise-cancelling headphones means the energy of the noise is:

145. In a graph showing two waves travelling in opposite directions, at the instant they are exactly in phase the resultant:

146. Which waves would diffract most through a 1 m doorway?

147. If the anti-noise wave were in phase with the noise, the listener would hear:

148. A string of length 1 m fixed at both ends carries waves at 100 m/s. Its fundamental frequency is:

149. When light passes through a single narrow slit, the pattern on a screen is:

150. After two wave pulses pass through each other, they:

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