This activity demonstrates that moving air exerts pressure and also explains that the motion of air exerts force on nearby objects, like the flame of a candle.
Sound and Communication Activity Solution
This activity is based on the NIOS Class 10 science
and technology (212) Chapter 18- Sound and Communication Module 4- Energy
Aim
To show that air in motion exerts a pressure or force
and pushes objects
Materials Required
1. Candlestick
2. Match
box
3. Electric
fan
4. A
loudspeaker
Procedure
We light a candlestick and place it on a table in front
of a running fan and observe what happens to the candlestick.
Now we place the
burning candle in front of the working loudspeaker that is producing sound. We observe
the movement of the candle flame.
Observation
The candle flame flickers and blows out due to the
moving air of a running fan. The candle flame also flickers when placed before
a working loudspeaker.
Explanation
Air in the motion exerts a force or pressure on nearby
objects. When a fan runs, its blade moves the air, and this moving air pushes
the candle flame and extinguishes.
The diaphragm
of a loudspeaker vibrates back and forth when producing sound. These vibrations
push the surrounding air and create a region of compression and rarefaction; these
pressure vibrations make the flame flicker.
Conclusion
This activity proves that sound travels through air by
creating vibrations and pressure changes.
Frequently Asked Questions
1. Why
does a candle flame flicker in front of a fan?
Answer – The moving air from the fan exerts pressure
on the flame.
2. What
causes sound to travel through air?
Answer – Sound travels through the vibration of air
particles, forming compression and rarefaction regions.
3. Why
does the flame move when placed near a loudspeaker?
Answer – The loudspeaker diaphragm vibrates the air
particles, which exerts pressure onthe flame.
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