Acoustic Phenomena

Question 1

Why sound waves are called pressure waves?

Answer 1

Because they travel through a medium (like air, water, or solids) by compressing and expanding the particles of that medium.

Question 2

Doppler’s Effect

Answer 2

The phenomenon of variation of pitch in the sound due to relative motion of source and observer(listener).

Question 3

Intensity of a sound

Answer 3

Flow of energy per unit area held normally towards the wave of propagation.

Question 3

Beats and beat frequency.

Answer 3

Each rise or fall in intensity of a sound is known as beats. No of beats per unit second is beat frequency.

Question 4

One bel and decibel.

Answer 4

Defined as the loudness of 1000Hz whose intensity of sound is 10 times of threshold hearing. Decibel is 10 times smaller than one bel.

Question 5

Threshold of hearing

Answer 5

The lowest intensity of sound a person can detect.

Question 6

Ultrasonic and infrasonic waves.

Answer 6

Sound produced in audible range (20KHZ) is ultrasonic.Sound produced below audible range (below 20KHZ) is infrasonic.

Question 7

Why is sound in empty jar loud than that of filled jar?

Answer 7

Empty jar contains more amount of air than that of filled jar and intensity of sound is greater where the amount of air is greater.

Question 8

Bat’s any question

Answer 8

Beacause they take help from infrasonic and ultrasonic wave.

Question 8

Factors in which sound depends

Answer 8

Temp , pressure , density and mass

Question 9

Person can knows another person’s sound without looking at them.(Violen/guitar).

Answer 9

Due to the difference in pitch of sound and overtones in the sound of the people.

Question 10

Quality of a sound.

Answer 10

Characteristics of a sound which helps to distinguish the sound of different mediums.

Question 12

Frequency of a sound when source is moving away from observer

Answer 12

v=v
lambda=v+Us/f
f’=v*f/v+Us