Sound can travel through

1

(a)

gases only

(b)

solids only

(c)

liquids only

(d)

solids, liquids and gases

Sound cannot travel through

1

(a)

solid

(b)

liquid

(c)

air

(d)

vacuum

Vibrations in a body produce

1

(a)

sound

(b)

pressure

(c)

density

(d)

current

Ultrasound has frequency of vibration

1

(a)

between 20 and 20,000 Hz

(b)

below 20 Hz

(c)

above 20,000 Hz

(d)

between 500 and 10,000 Hz

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

1

(a)

0.02s

(b)

2 s

(c)

0.2 s

(d)

20.0s

Time taken by an object to complete one oscillation is called..........

1

(a)

time period

Sound is produced by...............objects.

1

(a)

vibrating

Vibration is repeated................and...................motion.

1

(a)

to,fro

The time period is measured in............

1

(a)

second

The frequency is expressed in _______

1

(a)

Hertz

Sound waves travel faster in air than in water.

1

(a) True

(b) False

Plantation along roadside can reduce noise pollution.

1

(a) False

(b) True

Noise pollution may cause partial deafness

1

(a) True

(b) False

Health disorders can be caused by noise pollution.

1

(a) False

(b) True

A bird makes a high-pitched sound whereas a lion makes a low pitched roar.

1

(a) False

(b) True

What is the other name of voice box?

2

(a)

Larynx

Define 1 Hertz.

2

(a)

1 Hz is one oscillation per second.

What is the hearing range of human ears?

2

(a)

Hearing range of human ears is 20 Hz to 20,000 Hz

We cannot see vibrations in most of the cases. Explain why

2

(a)

The moment we hear a sound, does any part of our body vibrate? If yes, name the part

2

(a)

What is ultrasound?

2

(a)

Name the factor on which loudness of a sound depends.

2

(a)

Compare the sound of drum and whistle.

2

(a)

Your parents are going to buy a house. They have been offered one on the roadside and another three lanes away from the roadside. Which house would you suggest your parents should buy? Explain your answer.

3

(a)

Suppose a stick is struck against a frying pan in vacuum. Will the frying pan vibrate? Will we be able to hear the sound? Explain.

3

(a)

List sources of noise pollution in your surroundings

4

(a)

Define: (i) an oscillation (ii) Hertz

4

(a)

The town hall building is situated close to Boojho's house. There is a clock on the top of the town hall building which rings the bell every hour. Boojho has noticed that the sound of the clock appears to be much cleared at night. Explain

5

(a)

1. Sketch larynx and explain its function in your own words

   5

   (a)

2. How can noise pollution be controlled?

   5

   (a)