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What is ultrasound? State two uses of ultrasound.

Ultrasounds mean the sounds having frequency greater than 20,000Hz.

The uses of ultrasound are:

1. They are used in sonography.

2. They used in radars.

How do astronauts talk to one another on the surface of moon and why?

What is meant by the (a) 'pitch' of sound, and (b) 'quality' of sound?

What differences will you hear in a sound if there is an increase in

(i) amplitude, and (ii) frequency?

Calculate the time period of a pendulum which is vibrating with a frequency of 10 hertz.