Sound is a longitudinal wave that needs a material medium, such as air, water, or steel, to travel from one place to another. An experiment was conducted where an electric bell was placed inside a sealed bell jar - when the vacuum pump was turned on to remove the air, the sound of the bell became faint and disappeared, demonstrating that sound cannot travel through a vacuum and requires a medium like air, water, or steel to transmit vibrations and travel as sound waves.

1. Sound
Sound needs material
medium for travelling
By:
Eiman Rana

2. What is sound?
• Sound type of a wave
• Longitudinal wave
• Has wavelength, frequency and amplitude
• Travel parallel to direction of vibration of a medium

3. Sound needs material medium
for travelling
• Mechanical Wave
• Need medium in order to travel
form one place to another
• Material medium like: air,
water, steel etc
• Cannot travel through vacuum
• It travels through solid, liquid,
gas
• Vibrations also create sound

4. Experiment Demonstration
• Electric bell is suspended in a sealed bell jar
• Conditions:
Electric bell on
Vacuum pump off
• Conditions:
Electric bell on
Vacuum pump on
• Conditions:
Electric bell on
Vacuum pump off
You can see the movement of the
striker and hear the sound of bell
Air is drawn out of the bell jar the sound of the
bell becomes faint and disappears, even though
the striker is still hitting the bell
As air flows back into the bell jar, the
sound of the bell can be heard again

5. • This experiment demonstrates that sound cannot travel
through vacuum

6. Thank
You!