"Sound" Class 8 Science (CBSE):-

 

Extra 30 short questions and answers from the chapter:10

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.