These MCQs on chapter sound class 9 Physics are designed to test your knowledge and make learning and interactive. By answering these questions, you can check your understanding and see how well you know the topic of light. Let’s get started and brighten up our knowledge about light!
MCQs Questions With Answer For ICSE Class 9 Physics
1. When the vibrating object moves backwards, it creates a region of low pressure called_______.
A. refraction
B. reflection
C. retardation
D. rarefaction
View Answer
D
2.What is the primary requirement for the production of sound?
A. A light source
B. A vibrating object
C. A heat source
D. A magnetic field
View Answer
B
3. Sound in air propagates in form of:
A. Longitudinal wave
B. Transverse wave
C. Both longitudinal and transverse wave
D. None of these
View Answer
A
4. Longitudinal wave can be produced in:
A. solids
B. liquids
C. gases
D. All of the above
View Answer
D
5. The number of compressions or rarefactions per unit time gives:
A. frequency
B. time period
C. amplitude
D. pitch
View Answer
A
6. The phenomenon of bending of sound waves around obstacles is called. The number of compressions or rarefactions per unit time gives:
A. Refraction
B. Diffraction
C. Polarization
D. Interference
View Answer
B
7.The phenomenon of persistence of sound after the source has stopped is called:
A. Reverberation
B. Echo
C. Resonance
D. Reflection
View Answer
A
8.The S.I. unit of wavelength is:
A. metre
B. hertz
C. second
D. m/s
View Answer
A
9. Sound waves in air is an example of:
A. Longitudinal waves
B. Transverse Waves
C. Electromagnetic Waves
D. None of the option
View Answer
A
10.When a body vibrates, it compresses the air surrounding it and forms a high-density area known as:
A. Refraction
B. Reflection
C. Rarefaction
D. Compression
View Answer
D
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revision notes:
sound
It is a form of mechanical energy which produces the sensation of hearing.
It is produced due to vibrations of different objects. It travels in the form of waves.
Propagation of Sound
A material medium is necessary for the propagation of sound. It can be solid, liquid or gas.
A wave in which the particles of the medium move to and fro in the same direction as the wave’s propagation is known as a longitudinal wave.
The longitudinal wave travels in the form of compressions and rarefactions
Basic Terms Connected to Waves
- Wavelength-It is the distance between two consecutive points on the wave which are in the same phase.
- Amplitude-It is the maximum displacement of the particle from its mean position.
- Frequency-It is the number of periodic oscillations completed in one second.
f = 1/T
T is the time taken to complete one oscillation
SI Unit of Frequency is Hertz(Hz)
- Wave Velocity(v)-The velocity at which energy is transmitted through a medium
Relation Between Wavelength, Frequency and Speed
Speed =Frequency ✕ Wavelength
Speed of Sound in Different Media:
Speed of sound is finite and is much less than the speed of light.
Speed of sound in solids > speed of sound in liquids > speed of sound in gases
The speed of sound increases with increase in temperature.
Reflection of Sound:
The laws of reflection for sound are the same as those for light.
- The angle of reflection is always equal to the angle of incidence.
- The reflected sound, the incident sound, and the normal sound belong in the same plane.
The repetition of sound caused by reflection of sound waves from an obstacle is known as an echo.
The time interval between the original sound and the reflected one must be at least 0.1 s for an echo
to be heard distinctly.
The phenomenon of persistence or prolongation of audible sound after the source has stopped
emitting it is called reverberation.
