CBSE Class 11 Physics Waves Quiz 3

1. A resonance air column of length 40 cm resonates with a tuning fork of frequency 450 Hz. Ignoring end correction, the velocity of sound in air will be

A 720 m/s B 820 m/s C 920 m/s D 1020 m/s

2. An observer is moving towards a stationary source of frequency 250 Hz with a velocity of 40 m/s. If the velocity of sound is 330 m/s, the apparent frequency heard by the observer will be

A 320 Hz B 300 Hz C 280 Hz D 260 Hz

3. With the increase in temperature, the frequency of the sound from an organ pipe

A Decreases B Increases C Remain unchanged D Changes erratically

4. Loudness of a note of sound is

A Directly proportional to amplitude of the wave B Directly proportional to square of amplitude of wave C Directly proportional to velocity of the wave D Directly proportional to square of velocity of the wave

5. The frequency of the note produced by plucking a given string increases as

A The length of the string increases B The tension in the string increases C The tension in the string decreases D The mass per unit length of the string increases

6. A siren placed at a railway platfrom is emitting sound of frequency 5 kHz. A passenger sitting in a moving train A records a frequency of 5.5 kHz while the train approaches the siren. During his return journey in a different train B he records a frequency of 0 kHz while approaching the same siren. The ratio of velocity of train B to that of train A is

A 242 / 252 B 2 C 5 / 6 D 11 / 6

7. Energy is not carried by

A Longitudinal progressive waves B Electromagnetic waves C Transverse progressive waves D Stationary wave

8. The extension in a string, obeying Hookes law is X. The speed of sound in the stretched string is V. If the extension in the string is increased to 1.5 X, the speed of sound will be

A 1.22 V B 0.61 V C 1.50 V D 0.75 V

9. Energy is to be carried from one place to another. Which one of the following cannot be used?

A Longitudinal progressive waves B Transverse progressive waves C Electromagnetic waves D Standing (stationary) waves

10. To demonstrate the phenomenon of beats we need

A Two sources which emit radiation of nearly the same frequency B Two sources which emit radiation of exactly the same frequency C Two sources which emit radiation of exactly the same frequency and have a definite phase relationship D Two sources which emit radiation of exactly the same wavelength