Does sound travel if there is no medium? in Sound – Class 8 Science Experiment

Chapter Name: Sound

Activity Name: Does sound travel if there is no medium? in Sound

Activity Description:

Required Items:

1. Glass or plastic tumbler
2. Cell phone
3. Small plate

Step by Step Procedure:

1. Ensure the tumbler is dry and tall enough to accommodate the cell phone vertically.
2. Place the cell phone inside the tumbler and play the ringtone.
3. Listen to the ringtone and note its volume level.
4. Cover the tumbler with the small plate and listen to the ringtone again, noting the difference in volume.
5. Suck the air from the glass while keeping it close to your mouth.
6. Observe how the volume of the ringtone changes as you suck more air out of the glass.
7. Ask a friend to listen to the sound as well, comparing the variations in volume.

Experiment Observations:

• When the tumbler is covered with a plate, the volume of the ringtone reduces, but it is still audible.
• Sucking air from the glass gradually decreases the volume of the ringtone.
• Complete suction of air results in the sound becoming inaudible.

Precautions:

• Take care not to damage the cell phone or the tumbler during the experiment.
• Be gentle while handling the glass or plastic tumbler to avoid any breakage.

Lesson Learnt from Experiment:

This experiment demonstrates that sound requires a medium for its propagation. The presence of air inside the tumbler allows the sound to be heard, but as the air is gradually removed, the sound becomes fainter until it becomes inaudible. It illustrates that sound cannot travel through a vacuum, emphasizing the need for a medium, such as air, for sound waves to propagate.