Sound

Question 1

do sound waves require medium for ?
sound waves are combination of?
speed of sound wave?
compression & rarefraction is produced due to?
compression where molecules of medium have ______ velocity and pressure
rarefraction where molecules of medium have ______ velocity and pressure.

Answer 1

propagation yes
compression & rarefraction
d covered by sound wave per unit time
v=d/t
vibrational K.E of sound source
low high
high low

Question 2

what does speed sound wave depend upon? why in solids sound waves travel faster?

Answer 2

density of medium
intermolecular distance.
high density and less intermolecular distance.

Question 3

how is sound produced?

Answer 3

As the object vibrate, it produces a series of successive compression &rarefaction in the air, thus, propagating sound throughthe airand finally reaches our ears.

vibrating source compels the medium particles to perform to & fro motion.

Question 4

infrasonic & ultrasonic wave? uses?

Answer 4

waves that have frequency less than 20 Hz
waves that have frequency more than 20,000 Hz

Question 5

SI unit of wavelength?
1 Hz means?
what does amplitude tell us?
wavelength representation?
time period representation?

Answer 5

meter
1 sound wave produced in 1 sec
energy level carried by sound wave low amplitude low energy of sound wave
lambda λ
T (s)

Question 6

draw a wave & label it?
f (sound)? SI unit?
amplitude & wavelength?

Answer 6

• no. of sound waves produced in 1 sec (Hz)
• distance b/w consecutive crests or troughs
• max. displacement covered by particle disturbed when sound wave travels through medium

Question 7

high pitch means?
low pitch means?

Answer 7

higher frequency = higher pitch (higher voice)
lower frequency = lower pitch (lower voice)

Question 8

why pitch has direct relation with frequency? unit of pitch?

Answer 8

no. of vibrations produced by unit interval of time.
not a physical quantity just a charcteristic of sound wave.

Question 9

how can loudness be measured?
it can tell us?
loud sound has __________.
faint sound has _______.
loudness of sound wave is _________.

Answer 9

not a physical quantity
measured on the basis of amplitude
diff. b/w loud & faint sound
high amplitude
low amplitude
intensity of sound wave

Question 10

frequency does not depend upon amplitude. T/F
loudness of sound depends upon?
waves are carrier of ___________.

Answer 10

True
4 factors pg 32
energy

FMIGTN

Question 11

can loudness of a speaker change while its pitch is constant?

Answer 11

yes
The loudness changes, but the pitch remains constant.

Question 12

define timbre?
what does it depend on?
what does harmonic contact mean?

Question 13

what is the intensity of sound wave?
formula? unit?
formula for speed of sound wave at temp.

Answer 13

energy transmitted by sound wave per unit perpendicular area per unit time.
I= E/A x t = P/A W/m2

Question 14

diff b/w loudness and pitch?

Question 15

diff b/w loudness and intensity?

Answer 15

pg 33

Question 16

what would happen to the loudness of sound with increase in frequency?
which property of sound wave determines loudness and pitch

Answer 16

loudness does not change with frequency
Loudness= amplitude of the sound.
Pitch= frequency of the sound.

Higher the amplitude, the louder is the sound.

Question 17

derive the unit of intensity level?

Question 18

high sound intensity?
faintest sound intensity?
describe intensity level. state formula

Answer 18

1W/m2
10 ^-12 W/m2
a quantity expressing the ratio of two sound intensities in logarithmic form
& comparing them to standard fixed value.

Question 19

factors of speed of sound wave?

Answer 19

2

viscosity

Question 20

characteristics of noise?

Answer 20

4

Question 21

how can sound waves be studied?
what sound waves are designed for human ears?
range of periodic sound waves?
what happens after this range?

Answer 21

• Sound waves can be studied in 2 manners, periodic sound waves and non-periodic sound waves.
• Human ears are designed for periodic sound waves.
• The range of periodic sound waves is about 15 Hz to 4000 Hz.
• periodic sound waves are converted to non periodic sound waves

Question 22

how reflection of sound produces echo?

Answer 22

When sound wave is generated, then upon its reflection from any surface (obstacle) produces another wave which is separately heard from the original sound produced by source of sound.

Question 23

what can be found with the help of echo? how?

Answer 23

distance of any object under water
d=vxt
v= speed of sound
t= time taken by echo

Question 24

what is the meaning of that human ears can perceive sound wave within 0.1 second?

Answer 24

this value shows that 2 sound waves can perceived if time interval b/w them is 0.1 sec.

Question 25

derive the formula for min. distance required for production of echo?
audible frequency range?

Answer 25

d= v x t / 2
if t is 0.1 then
1/20th the speed of sound
v/20
20 Hz to 20,000 Hz

Question 26

applications of echo?

Answer 26

speed of sound can be determined
depth of sea and presence of sumbarine can be located by echo technique
usage in obstetric ultrasonography

Question 27

what is acoustic protection?
reflection is more prominent if the surface is _____ and less if _______

Question 28

what is reverberation?

Answer 28

the reflected sound that can’t be distinguished from original sound.

Question 29

noise pollution effects?

Answer 29

pg 36