2. SOUND
The sensation felt by our ears are called
sound.
Sound is a form of energy.
Sound is that form of energy which makes us
hear.
Sound is edited by a vibrant source and is
transmitted through a material medium
producing sensation of hearing in ours ears.
3. PRODUCTION OF SOUND
Sound is produced when an object vibration.
In other words Sound is produced by
vibration objects.
A vibration object, which producer Sound has
a certain amount of energy which travels in
the form of Sound waves
The energy required it make an object
vibrate and produce Sound is provided by
some outside source like our hand, wind etc.
4. PROPOGATION OF SOUND
When a body vibrates, then the particle of the
medium around the vibrating body are set into
vibrations. The particle of the medium which are
very close to the vibrating body are pushed
away from the body. Hence the number of
particle of the medium in the region where the
displaced particles strike against the
neighbouring particle in large this region
compression as compression (C). When the
vibrating body moves backward, a region of
emptiness known as rarefaction (R) or a region
of low pressure or low density is created.
5. CHARACTERISTIC OF THE MEDIUM REQUIRED
FOR THE PROPAGATION OF SOUND
Medium must be elastic so that the medium
particles have the tendency to return back to
there original postions after the displacement
Medium must have the inertia so that it's
particles have the capacity to store the
energy.
The frictional resistence of the medium
should be negligible to minimise the loss of
energy in Propagation.
6. SOUND NEEDS A MEDIUM TO TRAVEL
Sound travels from one place to another
place when the energy is transferred from
one particle to another particle of a medium
like air or gas, liquid, solid etc.
It means Sound needs the material medium
for it's Propagation.
In other word, Sound cannot travel through
vaccum.
7. SOUND WAVES ARE LONGITUDINAL WAVES
When a sound wave travel through medium,
then compression and refraction follow one
another.
The particles of the medium through which a
sound wave travel vibrate to and from out there
mean position parallel to the direction of
Propagation of the sound wave
If the particles of the medium vibrate to and fro
about there mean positions parallel to the
direction of Propagation of the wave, therefore,
the sound waves are Longitudinal wave.
8. CHARACTERISTICS OF SOUND WAVE
Frequency
Amplitude
Time period
Wavelength
Velocity of wave
9. FREQUENCY
The number of Complete waves produced I
one second is called frequency of the wave.
The number of vibration per second is called
frequency
The unit of frequency is hertz (which is
return as Hz).
One hertz is equal to one vibration per
second.
It is usually represented by 'v'- Greek letter
Nu.
10. AMPLITUDE
The maximum displacement of each particle
from it's mean position is called amplitude.
They SI unit of amplitude is meter (m).
11. TIME PERIOD
The time required to produce one Complete
wave or cycle is called time period of the
wave.
Now, one Complete wave is produced by one
full vibration of the vibrating body.
So, we can write '' the time taken to
Complete one vibration is called time period.
Frequency = 1/time period or v = 1/T.
12. WAVELENGTH
The distance between two nearest point in a
wave which are in the same phase of
vibration is called the Wavelength.
The SI unit of Wavelength is meter (m).
The distance between two nearest (adjacent)
create of a wave is called it's Wavelength
The distance between the two nearest
(adjacent) troughs of a wave is called its
Wavelength.
13. VELOCITY OF WAVE
The distance travelled by a wave in one
second is called Velocity of the wave.
The SI unit for the Velocity of a wave is
meter per second (m/s).
14. REFLECTION OF SOUND
When a sound wave travelling in a medium
bounces back to same medium after striking
the second medium, reflection of Sound
wave is said to take place.
The reflection of Sound wave is similar to the
bouncing back of a rubber ball after striking
a ball or the surface of a floor.
15. LAWS OF REFLECTION
The reflection of Sound obeys the laws of
reflection. The laws of reflection of Sound are
as follows :
Incident angle = reflected angle
The incident ray of Sound, reflected ray of
Sound and the normal to the point of
incidence, all lie in the same plane.
16. ECHO
Echo is a repetition of Sound due to the
reflection of original Sound by a large and
hard obstacle.
The time after which an echo is heard is
given by to = distance/speed of Sound in air.
