Extra 30 short questions and answers from the "Sound" chapter:10 of Class 8 Science (CBSE):-

 

What is sound?

 

→ Sound is a form of energy that travels in the form of waves and is produced by vibrating objects.

 

What is the source of all sounds?

 

→ Vibrating objects are the source of all sounds.

 

What is vibration?

 

→ The to-and-fro motion of an object is called vibration.

 

How does sound travel?

 

→ Sound travels in the form of waves through a medium.

 

What type of wave is a sound wave?

 

→ Sound is a longitudinal wave.

 

Through which medium does sound travel fastest?

 

→ Sound travels fastest in solids, followed by liquids and then gases.

 

Can sound travel through a vacuum?

 

→ No, sound cannot travel through a vacuum as it needs a medium.

 

What is the unit of frequency?

 

→ The unit of frequency is

Hertz (Hz)

.

 

What is the range of audible sound for humans?

 

→ The human audible range is

20 Hz to 20,000 Hz

.

 

What is an echo?

 

→ An echo is the reflection of sound when it bounces off a hard surface.

 

What are the three characteristics of sound?

 

→

Loudness, Pitch, and Quality (Timbre)

.

 

What is pitch?

 

→ Pitch is how high or low a sound is, and it depends on frequency.

 

What is loudness?

 

→ Loudness is the measure of the intensity of sound and depends on amplitude.

 

What is the unit of loudness?

 

→ The unit of loudness is

decibel (dB)

.

 

What is the safe limit of sound for human ears?

 

→ The safe limit is around

85

dB

.

 

What is the relation between amplitude and loudness?

 

→ Higher amplitude = louder sound; lower amplitude = softer sound.

 

What is the relation between frequency and pitch?

 

→ Higher frequency = higher pitch; lower frequency = lower pitch.

 

Why do different musical instruments produce different sounds?

 

→ Due to differences in frequency and wave patterns.

 

What is noise?

 

→ Unpleasant and irregular sound is called noise.

 

What is music?

 

→ Pleasant and rhythmic sound is called music.

 

21-30: Applications & Effects of Sound

What is noise pollution?

 

→ Excessive and unwanted sound in the environment is called noise pollution.

 

Name two sources of noise pollution.

 

→

Traffic and loudspeakers

.

 

How can noise pollution be controlled?

 

→ By using soundproofing, planting trees, and reducing loud noises.

 

What part of the human body detects sound?

 

→ The

ear

detects sound.

 

What is the function of the eardrum?

 

→ It vibrates when sound waves hit it and helps in hearing.

 

What is the minimum distance required for hearing an echo?

 

→ At least

17.2 meters

.

What is ultrasonic sound?

 

→ Sound with a frequency above

20,000 Hz

is called ultrasonic sound.

 

What are the applications of ultrasound?

 

→ Used in

sonography, cleaning, and sonar

.

 

What is sonar?

 

→

Sound Navigation and Ranging (SONAR)

is used to detect objects underwater.

 

Why does sound travel faster in solids than in gases?

 

→ Because molecules in solids are more closely packed, allowing faster transmission.