Question
How can you prove experimentally that sound cannot propagate through vacuum ?
✓
Answer
Aim : To show that sound cannot propagate through vacuum.
Materials Required : An electric bell, a glass bell jar, vacuum pump, battery and a swtich.
Procedure :
Step 1. : Place the electric bell in the glass bell jar, as shown in fig. 3.4. Make sure that all the openings of the bell jar are properly closed. Now complete the electric circuit by switching on the switch.
Observation : When the circuit is closed, you can hear the sound of the bell. Also you can see its hammer striking against the gong.
Step 2.
Now, slowly remove the air from the bell jar by using the vacuum pump connected to the jar. Can you hear the bell now ?
Observation : As air is removed from the bell jar, the loudness of the bell decreases until it becomes very faint. Finally, you will not be able to hear the bell even though you can see the hammer of the bellstriking the gong. If you allow air to enter the bell jar, you will hear the sound of the bell again.
Conclusion : Sound cannot propagate in the absence of a material medium, that is, sound cannot travel through vacuum.
Materials Required : An electric bell, a glass bell jar, vacuum pump, battery and a swtich.
Procedure :
Step 1. : Place the electric bell in the glass bell jar, as shown in fig. 3.4. Make sure that all the openings of the bell jar are properly closed. Now complete the electric circuit by switching on the switch.
Observation : When the circuit is closed, you can hear the sound of the bell. Also you can see its hammer striking against the gong.
Step 2.
Now, slowly remove the air from the bell jar by using the vacuum pump connected to the jar. Can you hear the bell now ?
Observation : As air is removed from the bell jar, the loudness of the bell decreases until it becomes very faint. Finally, you will not be able to hear the bell even though you can see the hammer of the bellstriking the gong. If you allow air to enter the bell jar, you will hear the sound of the bell again.
Conclusion : Sound cannot propagate in the absence of a material medium, that is, sound cannot travel through vacuum.
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