Doppler Effect, Class 11 Physics NCERT Solutions

1. There will be total 10 MCQ in this test.
2. Please keep a pen and paper ready for rough work but keep your books away.
3. The test will consist of only objective type multiple choice questions requiring students to mouse-click their correct choice of the options against the related question number.
4. No negative marking for incorrect choice.
5. Please click on “Finish the Test” when you want to exit.
6. All the best – Happy Studying

1. In Doppler effect change in frequency depends on

 distance between source and listener

 speeds of source and listener

 density of air

 half of distance between source and listener

Question 1 of 10

2. A sound source of frequency 600 Hz is moving towards an observer with velocity 20m/s. The speed of sound is 340m/s. The frequency heard by observer will be

 630.5hz

 30hz

 637.5hz

 63.5 Hz

Question 2 of 10

3. A radar sends a radio signal of frequency 9 x 10⁹ Hz towards an aircraft approaching the radar. If the reflected wave shows a frequency shift of 3 X 10³ Hz, the speed with which the aircraft is approaching the radar in m/s is (velocity of radio signal is 3 X 108 m/s).

 100

 150

 50

 25

Question 3 of 10

4. A police car moving at 22 m/s, chases a motor cyclist. The police man sounds his horn at 176 Hz while both of them move towards a stationary siren of frequency 165 Hz. Calculate the speed of the motor cyclist, if it is given that he does not hear any beats. (Velocity of sound = 330 m/s).

 zero

 33 m/s

 22 m/s

 11 m/s

Question 4 of 10

5. If a source of sound was moving toward a receiver at 1/3 the speed of sound, what would the resulting wavelength be?

 6 times the emitted wavelength

 2/3 of the emitted wavelength

 1/3 of the emitted wavelength

  Can not be found

Question 5 of 10

6. Doppler’s effect in sound is:

 Superimposing

 Asymmetrical

  Infinite

 Symmetrical

Question 6 of 10

7. Which medical instrument uses doppler effect?

 Echocardiography

  Ultrasound machine

 Stethoscope

 MRI machine

Question 7 of 10

8. A whistle producing sound waves of frequencies 9500 Hz and above is approaching a stationary person with speed v ms-1. The velocity of sound in air is 300 ms-1. If the person can hear frequencies up to 10000 Hz, the maximum value of v upto which he can the whistle is

 A

 B

 C

 D

Question 8 of 10

9. If the source of sound moves at the same speed or faster than speed of the wave then it results in

 Doppler effect

 Beats

  Shock waves

 Refraction of sound

Question 9 of 10

10. Two trains A and B approach a station from opposite sides, sounding their whistles. A stationary observer on the platform hears no beats. If the velocities of A and B are 15 m/s and 30 m/s respectively and the real frequency of the whistle of B is 600 Hz, the real frequency of the whistle of A is (Velocity of sound = 330 m/s).

 660 Hz

 600 Hz

 570 Hz

 630 Hz

Question 10 of 10

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