NIOS Class 10 Science and Technology Chapter 18: SOUND AND COMMUNICATION– Chapter-wise Important Questions and Answers

NIOS Class 10 Science and Technology Chapter 18: SOUND AND COMMUNICATION | MCQs, Short & Long Answer Questions | 18. SOUND AND COMMUNICATION

Chapter 18: SOUND AND COMMUNICATION

INTEXT QUESTIONS 18.1

1. Which sound wave will have its crests farther apart from each other - a wave with frequency 100 or a wave with frequency 500?

Answer: The wave with frequency 100 will have its crests farther apart as its wave length will be higher. For sound waves, the velocity ‘v’ is equal to the product of wavelength and frequency (v = n × λ or

 

vn = λ

)

 and thus wavelength and frequency are inversely proportional. So for the same velocity, the lower frequency wave will have a larger wave length. Therefore, for the wave with a frequency of 100 Hz, will have a higher wavelength and the crests will be farther apart compared to the wave with frequency 500 Hz.

 

2. If the velocity of sound is 330 metres per second (m/s), what will be wavelength if the frequency is 1000 Hertz?

Answer:  Here, v=330 m/s , f=1000 Hz

We have,

λ=vf=3301000=33100=0.33 m

Therefore, the wavelength of the sound wave is 0.33 metres (m) (or 33 cm).

 

3. What is the approximate audible range of frequency for humans?

Answer: The approximate audible range of frequency for humans is 20 Hz to 20,000 Hz (20 kHz).

INTEXT QUESTIONS 18.2

1. Does a wave transfer energy or material?

Answer: A wave transfers energy. Even when the material is displaced, it’s temporary and it comes back to its normal position such as in case of a ripple in water.

2. How do mechanical and electromagnetic waves differ?

Answer:  Difference between Mechanical Waves and Electromagnetic Waves:

Mechanical Waves	Electromagnetic Waves
A medium is essential for propagation. They cannot travel in vacuum.	They can travel through vacuum as well as any medium.
They travel through solids, liquids and gases.	They can travel through empty space and also through matter.
Sound waves travel through liquids and solids with much lower energy losses.	In liquids and solids, electromagnetic waves lose energy very fast.
Their speed is comparatively low. The velocity of sound is highest in solids (a few thousand m/s).	Their speed is extremely high, about 3 lakh km/s (3 × 10⁸ m/s).

 

3. What is the difference between a transverse and longitudinal wave?

Answer: Difference between Transverse and Longitudinal Waves:

Transverse Wave	Longitudinal Wave
The direction of propagation of the wave (energy transfer) is perpendicular to the direction of oscillation of particles.	Particles of the medium vibrate parallel to the direction of wave propagation.
Particles move up and down while the wave moves forward.	Particles move back and forth in the same direction as the wave.

4. Do transverse waves form in solid?

Answer: Yes. The sound waves travel in solids.

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