Class 9 Physics Chapter 12 Sound MCQs

Get free access to Class 9 Physics MCQs for Chapter 12 Sound, along with their answers. The MCQs with answers for Class 9 Physics are provided as per the latest CBSE exam pattern. Going through Class 9 Physics MCQs for Chapter 12 Sound will help students improve their critical thinking abilities and help them score good marks in board exams.

Class 9 Sound MCQs

Check the multiple-choice questions for the 9th Class Physics Sound Chapter. Each MCQ will have four options here, out of which only one is correct. Students have to pick the correct option and check the answer provided here.

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1. When the vibrating object moves backwards, it creates a region of low pressure called —————-

1. Refraction
2. Reflection
3. Rarefaction
4. Retardation

Answer: (c) Rarefaction

Explanation: Rarefaction is the opposite of compression. Rarefaction means the reduction of density of the object.

2. Mexican wave in a stadium is an example of

1. Longitudinal wave
2. Transverse wave
3. Electromagnetic wave
4. None of the options

Answer: (b) Transverse wave

Explanation: Mexican wave, also known as the stadium wave, is an ideal example of a vertically polarised, transverse, travelling wave.

3. State true or false: Sound does not need a medium to propagate.

1. True
2. False

Answer: (b) False

Explanation: Sound needs a medium to propagate. The matter or material through which sound propagates is called a medium.

4. The distance which compression or a rarefaction travels per unit of time gives————-

1. The density of sound wave
2. Speed of sound
3. Wavelength of sound
4. Frequency of sound

Answer: (b) Speed of sound

Explanation: Speed of sound measures the compression or a rarefaction that travels per unit of time.

5. Is the law of conservation of energy applicable to sound waves?

1. Yes
2. No

Answer: (a) Yes

Explanation: The law of conservation of energy is applicable to sound waves.

6. Sound travels through which medium?

1. Solid
2. Liquid
3. Gas
4. All the above

Answer: (d) All the above

Explanation: Sound has the ability to travel through solid, liquid and gas.

7. When a body vibrates, it compresses the air surrounding and forms a high-density area known as —————-.

1. Refraction
2. Reflection
3. Rarefaction
4. Compression

Answer: (d) Compression

Explanation: Compression is the opposite of rarefaction. Compression means increase in the density of the object.

8. The phenomenon where a sound produced is heard again due to reflection is called ———–

1. Sound bounce
2. Mirage
3. An echo
4. Interference

Answer: (c) An echo

Explanation: To hear a distinct echo sound, the time interval between original and reflected sound must be at least 0.1s.

9. The number of compressions or rarefactions per unit time gives ———–

1. Frequency
2. Time period
3. Amplitude
4. Pitch

Answer: (d) Pitch

Explanation: The number of compressions or rarefactions per unit time defines pitch. The pitch is directly proportional to frequency.

10. Sound waves in air is an example of ——————

1. Longitudinal wave
2. Transverse wave
3. Electromagnetic wave
4. None of the options

Answer: (b) Longitudinal wave

Explanation: In longitudinal waves, particles travel parallel to the direction of wave motion employing successive compressions or elongations.