Class 8 Sound

(a)   helps us to communicate.

The voice box is also called as

• stomach

• heart

• larynx

• mouth

Sound is a kind of

• work

• pressure

• force

• energy

The hearing range of human ear is

• 20 Hz to 20,000 Hz

• less than 20 Hz

• more than 20,000 Hz

• 20 Hz to 25,000 Hz

Pitch of sound is determined by its

• frequency

• speed

• amplitude

• loudness

1 hertz is equal to

• 1 vibration per minute

• 10 vibrations per minute

• 60 vibrations per minute

• 600 vibrations per minute

Sound cannot travel through

• air

• water

• vacuum

• solid

The sound in the audible range is called

• ultrasonic sound

• sonic sound

• subsonic sound

• light sound

A pendulum oscillates 20 times in 4 seconds. Find its time period.

• 0.05 sec.

• 0.001 sec.

• 0.2 sec.

• 0.1 sec.

Loudness of sound is determined by

• pitch

• frequency

• amplitude

• time period