Explain the process, how bat sure ultrasonic waves to catch a prey

3

(a)

Explain the consequences noise pollution

3

(a)

List three sources of noise pollution in your locality

3

(a)

We have learnt that vibration is necessary for producing sound. Explain why the sound produced by every vibrating body cannot be heard by us.

3

(a)

Briefly explain total hearing impairment.

3

(a)

Suggest three measures to limit noise pollution in your locality

3

(a)

Explain the reason for not hearing of the screams of a bat by us.

3

(a)

Astronauts in outer space have to use radios to communicate with one another. Why?

3

(a)

A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.

3

(a)

Which part of the following objects vibrates and sound is produced?
(i) Ringing of a sound bell
(ii) Buzzing of insects
(iii) Bursting of balloon
(iv) Brushing of table
(v) Playing a sitar
(vi) Dholak
(vii) flute

3

(a)

What is hearing impairment? How do people over come this problem?

3

(a)

What is frequency? How does it affect the quality of sounds?

3

(a)

Define: (i) an oscillation (ii) Hertz

3

(a)

What do you mean by vacuum? What happens to the loudness of sound in vacuum?

3

(a)

Explain the structure of human ear and its functions. 

3

(a)