Waves Test

Result

Waves Test - 93

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Weekly Quiz Competition

Question 1
4 / -1

A car sounding a horn of frequency 1000 Hz passes an observer. The ratio of frequencies of the horn noted by the observer before and after passing of the car is 11 : 9. If the speed of sound is v, the speed of the car is

A

B

C

D

Solution
Question 2
4 / -1

What should be the velocity of a sound source moving towards a stationary observer so that apparent frequency is double the actual frequency (Velocity of sound is v)

A

B

C

D

Solution
Question 3
4 / -1

A bus is moving with a velocity of 5 m/s towards a huge wall. The driver sounds a horn of frequency 165 Hz. If the speed of sound in air is 355 m/s, the number of beats heard per second by a passenger on the bus will be

A
6

B
5

C
3

D
4

Solution
Question 4
4 / -1

A source and an observer approach each other with same velocity 50 m/s. If the apparent frequency is 435 sec^–1, then the real frequency is

A
320 sec^–1

B
360 sec^–1

C
390 sec^–1

D
420 sec^–1

Solution
Question 5
4 / -1

Doppler effect is applicable for

A
Moving bodies

B
One is moving and other are stationary

C
For relative motion

D
None of the above
Question 6
4 / -1

When an engine passes near to a stationary observer then its apparent frequencies occurs in the ratio 5/3. If the velocity of engine is (Velocity of sound is 340 m/s)

A
540 m/s

B
270 m/s

C
85 m/s

D
52.5 m/s

Solution
Question 7
4 / -1

A police car horn emits a sound at a frequency 240 Hz when the car is at rest. If the speed of the sound is 330 m/s, the frequency heard by an observer who is approaching the car at a speed of 11 m/s, is :

A
248 Hz

B
244 Hz

C
240 Hz

D
230 Hz

Solution
Question 8
4 / -1

A bat flies at a steady speed of 4 ms^–1 emitting a sound of f = 90 x 10³ Hz. It is flying horizontally towards a vertical wall. The frequency of the reflected sound as detected by the bat will be (Take velocity of sound in air as 330 ^–1).

A
88.1 x 10³ Hz

B
87.1 x 10^–3 Hz

C
92.1 x 10³ Hz

D
89.1 x 10³ Hz

Solution
Question 9
4 / -1

A police car with a siren of frequency 8 kHz is moving with uniform velocity 36 km/hr towards a tall building which reflects the sound waves. The speed of sound in air is 320 m/s. The frequency of the siren heard by the car driver is

A
8.50 kHz

B
8.25 kHz

C
7.75 kHz

D
7.50 kHz

Solution
Question 10
4 / -1

A source is moving towards a stationary observer, so that the apparent frequency increases by 50%. If velocity of sound is 330 ms-1, then velocity of source is

A
220 ms^–1

B
180 ms^–1

C
150 ms^–1

D
110 ms^–1

Solution