Guess Paper Year 2011
CBSE Class IX
Subject: Physics

Topic: Sound

1. what type of wave is sound wave?
(a) radio waves
(b) electro magnetic wave
(c) mechanical wave
(d) transverse wave

2. SONAR works on principle of
(a) echo
(b) resonance
(c) particle nature of wave
(d) none

3. Loudness depends on
(a) wave length
(b) frequency
(c) amplitude
(d) intensity

4. Pitch increases with increase in
(a) energy of sound
(b) frequency
(c) wave length
(d) amplitude

5. speed of sound greatest in
(a) milk
(b) wood
(c) iron
(d) air

6. The sound whose frequency is between 20 Hz to 20000 Hz is
(a) infrasonic wave
(b) audible sound
(c) ultrasonic wave
(d) radio waves

Very Short Answer Questions:

1. What is echo?

2. What are conditions necessary to hear echo?

3. What is SONAR ? Give its use?

4. How density of medium affect speed of sound?

5. What is pitch of sound?

6. What is amplitude of sound waves?

7. What is resonance?

8. What is sonometer?

9. Define the terms frequency , wave length and time period .

10. If 2000 ripples produced in 5 sec in a pond find time period and frequency of ripples formation.

Numerical:

1. A person observe the smoke from a gun 1.4 sec before he hear the bang. If the gun is 476m away from the person, find the speed of sound?

2. A person standing near the cliff fires the gun and heared the echo after 1.5 sec . If the speed of sound in air is 340m/sec , how far is person from the cliff?

3. A sound wave of frequency 5000 Hz travel in air with speed of 350m/sec. Calculate the wave length.

4. If you hear thunder 7 sec after you see lightening , how far you from the lighting occurred?

5. A bat emits ultrasonic wave of frequency 30 Khz . If its speed is 350m/s and bats hear its echo after 0.6 sec after emitting the , find how far is bat from obstacle and wave length of wave?

6. Meera is standing between two hills. She shouted loudly and hears first echo after 0.5 sec and second echo after 1 sec. what is distance between two hills?

Long Answer Questions:

1. State any two characteristics of sound wave? why it is called mechanical wave?

2. What are differences between music and noise?

3. How bat is able to fly in night?

4. Discuss effect of temperature and humidity on speed of sound.

5. Why lightening appears before than thundering in rainy season?

6. How is the depth of oceans measured using echo?