# NCERT Class 9 Physics Formative Assessment of Sound CBSE Board Sample Problems (For CBSE, ICSE, IAS, NET, NRA 2022)

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1) Arrange the speed of sound in Steel, water and air in ascending order?

2) What is the relation between frequency and time period of the wave?

3) Sound waves are transverse waves True or False?

4) Arrange the speed of these waves in air in descending order a) light b) Sound C) Supersonic aircraft?

5) What is an echo?

6) What are three characteristics of the sound?

7) What is the audible range of sound frequencies for human ear?

8) What is Reflection of sound?

Match the column

 Column A(Frequency) Column B(Sound range they fall) 5 Hz Audible range 25000 Hz Infrasonic range 25 Hz Ultrasonic range 250 Hz 10 Hz 120000 Hz

Match the column

 Column A Column B The maximum disturbance caused by the wave Wavelength The distance travelled by a wave per second Frequency The no of complete vibrations per sec Velocity The distance between one crest of wave and next one Amplitude When we change a feeble sound too loud sound, we increase its Time period When we change the pitch. what is getting changed

Table type question

 Sound velocity Frequency Wavelength Time period Audible/Ultrasonic/Infrasonic 330 m/s 550Hz ? ? ? 500 Hz 68m ? ? 343.4m/s ? 1.7cm ? ?

Fill in the blanks

1) Sound waves ________travel in vacuum

2) The speed of sound depend son ________And ________

3) The soft and porous materials are bad ________of sound

4) The speed of the highly penetrating ultrasonic waves are ________those of audible sound waves

5) The________ sound are produced before the main shock wave of earth quake

Solution

1) Do not

2) Nature of the material, temperature

3) Reflectors

4) Same

5) Infrasonic

Crossword Puzzle

Across

4. It is used break kidney stones into fine grains

7. The unit of frequency

8. The loudness of the sound depends on this

9. Medical instrument used by the doctors for listening to heartbeats

10. It is the region of low pressure in longitudinal wave

Solution:

Across

Ultrasound, Hertz. Amplitude. Stethoscope, rarefaction

Down

1. Apparatus used to find the depth of the sea

2. It converts sound wave frequency into electrical impulses

3. A vibrating simple pendulum produces this type of sound

5. It is the sensation of a frequency

6. Elevation in a transverse wave

Solution:

Down

Sonar, Cochlea, infrasonic, Pitch, crest

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