Page 135 - Science Class 08

2. Sound-vibra ons below ________________________ cannot be heard by human ears.
3. The audibility of a sound depends on its ________________________ .

4. The features that help us ________________________ sounds are _____________ and
________________________ .

5. Sound needs a ______________________ for travelling from its source to its des na on.
E. Match the following columns.
Column I Column II

1. Pitch of a sound a. Infrasonic sound ultrasonic
2. Loudness b. Ultrasonic sound
3. 20000 Hz/sec. c. Fastest medium for sound
4. 20 Hz/sec. d. Amplitude

5. Solids e. Frequency
F. Very short answer ques ons.
1. What do we call the form of energy that produces sensa on of hearing?

2. What happens when a flute is played?
3. What is oscilla on?
4. How is period measured?
5. What do you mean by loudness?

6. What is the hearing frequency of human being?
7. Write one line for human ears.
G. Short answer ques ons.

1. Write about different kinds of sound made by different things.
2. What do you understand by frequency?
3. What is amplitude?
4. Write briefly about ultrasonic waves.

5. What do you mean by propaga on of sound.
H. Long answer ques ons.
1. What is meant by sound? How is it produced? Which organ of the body records its
sensa on and how?
2. What features of sound help us to dis nguish between various types of sounds?

3. What does sound need to travel from its source to the ear?
4. How does sound travel through solids, liquids and gases?
5. Which travels faster— light or sound? Explain your answer through a common example?

Project ActivityActivityActivity
Project
Project
Project Activity
Make a powerpoint presenta on explaining the following topics.
1. Amplitude 2. Frequency 3. Time period
4. Oscilla on 5. Loudness 6. Pitch

Science-8 135