# Class 9 Science Important Questions for Sound |physics

Assignments NCERT Solutions

Given below are the Class 9 Science Important Questions for Sound
a) Concepts questions
b) Calculation problems
c) Multiple choice questions
e) Fill in the blank's

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 to 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 ? ? ? 500hz 68m ? ? 343.4m/s ? 1.7 cm ? ?
Fill in the blanks
1)Sound waves   ……  travel in vacuum
2)The speed of sound depends on   ………….  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
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
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
Fill in the blank solution
1. Do not
2. Nature of the material ,temperature
3. Reflectors
4. Same
5. infrasonic
Crossword Solution
Across
Ultrasound,Hertz, Amplitude, Stethoscope, rarefaction
Down
Sonar, Cochlea, infrasonic, Pitch, crest