Explore topic-wise InterviewSolutions in .

Sound is produced by vibrating objects. When an object vibrates, it sets the particles of the medium around it vibrating. The particles do not travel all the way from the vibrating object in the ear. A particle of the medium in contact with the vibrating objects is first displaced from its equilibrium position.

It then exerts a force on the adjacent particle. As a result of which the adjacent particle. As a result of which the adjacent particle get displaced from its position at rest. After displacing the particle comes back to its original position. This process continues in the medium in the sound reaches our ears.

Correct option is B) P, Q both are true

Sounds of frequency lower than 20 Hz are called the infrasonics. We cannot hear the infrasonic sounds.

The answer is (B) 20 Hz to 20000 Hz

20 Hz to 20000 Hz.

Because moon does not have any atmosphere and sound its does not have any medium for sound to travel as sound does not travel in vacuum.

The astronauts have sound transmitting devices in the helmets they wear which help them exchange sound waves with one-another. This is because moon does not have any atmosphere and sound its does not have any medium for sound to travel as sound does not travel in vacuum.

The answer is (A) m

The answer is (C) infrasound

(a) Low-frequency infrasound main shock waves.

(b) Elephant and Peacock.

(c) Between 20 Hz to 25000 Hz.

Dogs can hear sounds that are beyond our audible range. So, whenever they hear a sound which is inaudible to us, they bark in a response to it.

Sound can travel through both iron as well as water.

The loudness of sound is directly proportional to the square of the amplitude of the wave.

Loudness α (amplitude) ² When the amplitude is doubled loudness becomes ( 2 )² = 4 times

Pitch is a characteristic of sound which distinguishes between a shrill sound and a deep, low sound.

The sounds which produce unpleasant effects are called noises.

Loudness will be four times because loudness is directly proportional to the square of amplitude.

(a) Amplitude - The louder sound corresponds to the wave of large amplitude.

(b) Loudness is directly proportional to the square of amplitude.

The characteristics by which one can distinguish a musical note from another are pitch, loudness, and quality.

Quantity which determines the loudness of a sound wave is (c) AMPLITUDE.

CHARACTERISTICS OF SOUND

Sounds can be distinguished from one another by the following three different characteristics:

(i) loudness

(ii) pitch or shrillness, and

(iii) quality or timbre.

RELATIONSHIP BETWEEN THE TIME PERIOD (T) and FREQUENCY (ƒ): By definition time period is the time taken to complete 1 vibration

Or

In time T, number of vibration= 1

∴ In 1 second, the frequency or number of vibrations = 1 / T

ƒ = 1 / T Or T = 1 / ƒ

Longitudinal wave: The wave in which the particles of the medium vibrate about their mean positions in the direction of propagation of sound is called a longitudinal wave. Such a wave can be produced in solids, liquids as well as gases.

A periodic disturbance in the medium (Air) is created by the vibration of sound and the particles of the medium vibrate about their mean position and transfer of energy in the form of sound waves takes place, i.e. in the LONGITUDINAL WAVES.

In a piano, pitch is decreased by using thicker string

The safe limit of loudness of audible sound is 0 to 80 dB

The unit of loudness is cm.

C. metal plates 

Metal plates vibrates when a musical note is produced by the cymbals in an orchestra.

Decibel is the unit used to measure the loudness of sound. Its symbol is dB

Vocal chords vibrates when we speak.

When we speak, vocal cord vibrates in our body.

All vibrating bodies produce sound, but we cannot hear some of them, due to the limit of audible frequency.

The number of oscillations completed by an oscillator in one second is called the frequency of oscillation.

No, sound cannot travel through vacuum as for propagation of sound it needs a medium.

A reflection of sound, arriving at the listener in more than 0.1 s after the direct sound is called an echo.

c) Male vocal cord is longer

The Normal conversation is at 60 dB

A reflection of sound, arriving at the listener in less than 0.1 s after the direct sound is called reverberation.