Sound 7&8 Flashcards
Frequency is denoted by
N
SI unit of intensity of sound
Joule/ sec x m square. OR
Watt/ m square
In a stethoscope sound produced by the heart is picked by a……………
Diaphragm
What happens when the length of an pendulum is decreased
Time period decreases, frequency increases
Wavelength is denoted by
λ
Ear most sensitive to frequencies btw …………………. frequency
2000 to 3000 Hz
Amplitude denoted by
A
Watt=
Joule/ sec
Sounds above 20 kHz
Ultrasonic
Longitudinal wave also called
Compression waves
Sound travels in which wave
Longitudinal
No of vibrations in one second
Frequency
Minimum distance needed to hear an echo
17 m
Persistence of hearing
1/10 of a sec
Children can hear upto ……………… Hz
30000
Formula for calculating distance for an echo
D=vt/2
For every 1 degree Celsius increase what is the increase in speed
.61m/ s
Nodes and antinodes means
Nodes are situated in places of minimum displacement . While antinodes are situated at places with maximum displacement
A dog and some fishes can hear upto
50 to 100 kHz,1-25Hz
Transverse wave-
The particles of a medium travel perpendicular
Sounds below 20 Hz
Infrasonic
What is a longitudinal wave
Particles of the medium travel in the same direction
Time taken by a particle to make one complete vibration or move a distance equal to the wavelength
Time period
Range is of hearing for humans
20 Hz to 20000 Hz
…………….. produces sound in the human body
Larynx at the upper end of wind pipe
Aged people can hear upto………………. kHz
10-12
Loud sounds more than ………harms the ear
80 db
Ultrasonic vs supersonic
Ultrasonic- frequency more than 20000Hz
Supersonic- speed more than sound
Sound is not affected by pressure why
Because density and pressure cancel each other out
Ideal gas is a gas in which
Molecules do not attract or repel each other
Molecules takes themselves no volume
Ideal gas law is
Pressure x volume = nRT
n - number of moles
R - universal gas constant
In a simple pendulum the time period of the pendulum is directly proportional to
T directly proportional to √length
Water speed of sound
1500 m/s
Granite speed of sound
6000m/s
Aluminium speed of sound
6420 m/s
Science of sound relating to the designing of buildings
Acoustics
Harmonics
Multiples of frequencies of sound
Velocity is directly proportional to
Square root of temperature
Quartz crystals produce ultrasonic sound when
Electricity is passed through it
Ultrasonic waves generated by
Small sources
Infrasonic waves produced by
Earthquake or seismic waves
Infrasonic sounds are generally generated from
Large sources
An important condition for the formation of echo is that
Wavelength is less than height of reflecting body
Music sound level
10-30 dB
Noise sound level
Above 120 dB
RADAR full form
Radio detection and ranging
What is a radar
Radar is an object-detection system that uses radio waves to determine the range, angle, or velocity of objects.
In Doppler effect when a sound emitting obj comes closer
The frequency gets higher and vice versa
Use of Doppler effect in radar
It helps the radar to understand if the object is coming towards or away from it
A radar emits
Radio waves which if there is an obj gets reflected back to the radar
SONAR full form
Sound navigation and ranging
SONAR helps in detection of
Submarines
Quartz produces ultrasound by the process
Piezoelectric effect
Loudness formula
10 x log (of) I/I°
I° - constant I - intensity of sound
Power SI unit
Watt which is energy by time
1 watt =
I joule/ time
Jet at take off
140 dB
Pop concert
130 dB
Police car siren
120 dB
Heavy hammering machine
110 dB
Diesel lorry
90 dB
Car / motorcycle
80 dB
Vacuum cleaner
60 dB
Normal conversation
50 dB
Soft whisper
30
Recording studio
20 dB
Leaves rustling
10 dB
Dropping pin
0 dB
Torque :
A force that causes an object to rotate.
Horse power ?
Torque applied over time
All objects oscillate because they have a
Restoring force
Equilibrium position of an oscillator
Position at which 0 net force is acting on the oscillator.
Every oscillator tries to get back to the equilibrium position but it can’t.
Why are some oscillators called simple harmonic motion
They have a restoring force that is directly proportional to the displacement.
Spring force (force provided by a spring)=
-[Spring constant (k) x displacement(x)]
= -kx
It is negative because force and displacement would act on opp directions.
It is proportional to displacement.
So an object attached to a spring shows simple harmonic motion , as the restoring force (spring force) is directly proportional to displacement.
The equilibrium point of a simple harmonic motion has
Maximum speed
0 restoring Force
0 acceleration
In simple harmonic motion , force is directly proportional to
Acceleration and not speed.
In a simple harmonic motion ; the end points have
Maximum restoring force , so maximum acceleration ,but still low speed (0)
Time by default should always be put in the ……. axis
Horizontal
Time period of simple Harmonic motion is not affected by
Amplitude.
If you pull the object very far from the equilibrium , then when it is restored the speed will be more. So as there is an increase in both speed and the distance it has to travel, time period remains same.
Time period of simple harmonic motion of an object attached to a spring depends on
Mass of the object and the spring constant. This is because the spring force (restoring force) increases on increasing the spring constant.
So if the spring constant is more then the time period will decrease.
Time period increases on increasing mass of an object.
Time period of simple harmonic motion of an object attached to a spring - formula
T = 2 π √(m/k)
m - mass
k - spring constant
Mechanical waves also called
Elastic waves
Loudness of sound is considered normal when it is between
50 - 60 dB
A dog can hear sound that has a frequency upto
50 kHz
Fishes can hear very low frequencies upto
1-25 Hz
Whales and elephants can hear infrasonic sound
T
Speed of sound at 0°C is
330 m/s
Persistence of hearing
1/10 of a second
Min distance for heating an echo
17 m
Music sound level
10 - 30 dB
Usually all sounds of level above …….. are considered as noise
120 dB
Outer ear contains
Pins and ear canal (2-3 cm)
Ear drum also called
Tympanum
Eustachian tube location
Lower part of middle layer.
Goes to throat to maintain air pressure.
Cochlea contains
Nerve cells that are sensitive to sound
Oval window is situated
Btw middle and inner part of ear
