2. Contents in this presentation
What is sound ?
How does it each our ear ?
How does it travel?
What are the circumstances or situations necessary
to occur for the sound to be produced and heard .
Pros and cons of sound . (high sound or low sound )
Causes of loss of hearing
3. What is sound ?
Sound is a form of energy which is produced by
various objects like a bowl filled with water, a steel
container , a balloon ( when it bursts )
etc.
Sound is produced even when a child cries.
4. How is sound produced ?
It is produced by a vibrating body.
For instance if we touch a ringing bell. What do we
feel ? Some vibration is there which produces sound.
Another example can be when we play drums the
cymbals hit together and produce sound because
they are moving or striking to each other and which
causes it to vibrate.
6. How does sound travel ?
Sound needs a
medium to travel .
Without a medium
it cannot travel .
7. What is the medium here ?
The medium here can be air , water
, iron etc
In simple words it needs a solid ,
liquid or a gas to travel.
It cannot travel through vacuum . It
can be demonstrated by the
following activity
8. Activity
Take an electric
bell and an
airtight glass
bell jar. The
electric bell is
suspended
inside
the airtight bell
jar. The bell jar
is connected
to a vacuum
pump, as
9. to a vacuum
pump, as
shown in
Figure. If
you press the
switch you
will be able to
hear
the bell ?
10. Conclusion
The answer is no ,
because there is no
medium to travel and
so the sound cannot be
heard .
