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Sound

Boojho saw a cracker burst at night at a distance from his house.
He heard the sound of the cracker a little later after seeing the
cracker burst. Give reason for the delay in hearing the sound.

Sound

Does any part of our body vibrate when we speak? Name the
part.

Sound

Lightning can be seen the moment it occurs. Paheli observes
lightning in her area. She hears the sound 5 s after she observed
lightning. How far is she from the place where lightning occurs?
(speed of sound = 330 m/s).

Sound

Ultrasound has frequency of vibration
(a) between 20 and 20,000 Hz
(b) below 20 Hz
(c) above 20,000 Hz
(d) between 500 and 10,000 Hz

Sound

Pitch of sound is determined by its
(a) frequency (c) speed
(b) amplitude (d) loudness

Sound

1 hertz is equal to
(a) 1 vibration per minute
(b) 10 vibrations per minute
(c) 60 vibrations per minute
(d) 600 vibrations per minute

Sound

The loudness of sound is determined by the
(a) amplitude of vibration
(b) ratio of amplitude and frequency of vibration
(c) frequency of vibration
(d) product of amplitude and frequency of vibration

Sound

Loudness of sound is measured in units of
(a) decibel (dB) (c) metre (m)
(b) hertz (Hz) (d) metre/second (m/s)

Sound

In order to reduce the loudness of a sound we have to
(a) decrease its frequency of vibration of the sound.
(b) increase its frequency of vibration of the sound.
(c) decrease its amplitude of vibration of the sound.
(d) increase its amplitude of vibration of the sound.

Sound

An object is vibrating at 50 hertz. What is its time period?

(a) 0.02 s (c) 0.2 s (b) 2 s (d) 20.0 s