Sound

Question 1

What is the range of hearing

Answer 1

The avg frequency range is 20Hz to 20,000Hz

Question 2

What is infrasonic sound

Answer 2

The sound frequencies lower than 20Hz are called infrasonic sounds

Question 2

What are ultrasonic sound s

Answer 2

The sounds of frequencies higher than 20,000Hz are called ultrasonic sounds

Question 3

What is an echo

Answer 3

—> it is a reflection of sound arriving at the listener sometime after the original sound

Question 4

Conditions for hearing an echo

Answer 4

—> the size of the obstacle must be large compared to the wavelength of the original sound

—> the distance between source of sound and original reflector should be at least 17m

—> the intensity or loudness of the sound should be sufficient for the reflected sound reaching the ear to be audible. The original sound should be of short duration

Question 5

What are damped vibrations

Answer 5

The periodic vibrations of the body of decreasing amplitude in the presence of a resistive force is called damped vibrations

Eg = oscillations of simple pendulums in air

Question 6

What are free vibrations

Answer 6

The periodic vibrations of the body of constant amplitude in the absence of external force on it are called free vibrations

Question 7

What are forced vibrations

Answer 7

The vibrations of a body which take place under influence of external periodic force acting on it is called forced vibrations

Question 8

What is resonance

Answer 8

When the frequency of an externally applied periodic force on a body is equal to its natural frequency, the body readily begins to vibrate with an increased amplitude

The vibrations of large amplitude is called resonant vibrations

Question 9

What are the conditions for resonance

Answer 9

—> frequency of applied force is equal to the natural frequency of the vibrating body

Question 10

The relation between frequency and length

Answer 10

Frequency is inversely proportional to Length

Question 11

Relation between frequency and tension

Answer 11

Frequency is proportional to the √tension

Question 12

What is wavelength formula

Answer 12

Wavelength = speed / frequency

Question 13

Differentiate between sound wave and light wave

Answer 13

Sound waves are mechanical waves
Sound waves are longitudinal in nature
Sound waves Require a medium for propagation
Speed if sound is 300 m/s

Light waves are electromagnetic waves
Light waves are transverse in nature
Light waves can travel vacuum
Speed of light waves in air is 3 x 10^8 m/s

Question 14

Define wavelength

Answer 14

The distance between 2 consecutive compressions and rarefactions is called the wavelength

It is the minimum distance in which the sound wave repeats itself

Question 15

Define frequency

Answer 15

The number of complete waves produced in 1 second is called frequency of the wave

It is the number of vibrations that occur per second

SI unit is hertz

Question 16

Define time period

Answer 16

The time taken by 2 consecutive rarefactions to cross a fixed point is called the time period of the sound wave

The time required to produce 1 complete wave

Time period = 1/frequency

Question 17

Define amplitude

Answer 17

The maximum displacement of the particles of the medium either side from their original mean position on passing through the medium is called the amplitude

Question 18

Define speed

Answer 18

The distance travelled by a wave in 1 second is called speed of the wave

Speed of sound remains same for all frequencies

Question 19

Define loudness

Answer 19

Loudness is the property by virtue of which a loud sound can be distinguished from a faint one

Both having same pitch and quality

Question 20

Define pitch

Answer 20

It is the characteristic of sound by which a shrill note can be distinguished form a grave note

Pitch of a note depends on frequency

Question 21

Define quality of sound

Answer 21

Quality of sound is that characteristic which distinguishes 2 sounds of same loudness and pitch but emitted by 2 different instruments

The quality of sound depends on wave form

Question 22

The relation between loudness and amplitude

Answer 22

Loudness of a sound wave depends upon the square of its amplitude

Question 23

The relation between frequency and amplitude

Answer 23

Frequency does not depend upon amplitude