Activity 10.6 Let us experiment to show that sound is a form of energy. Class 9

Activity 10.6 Let us experiment to show that sound is a form of energy. Class 9

Activity 10.6 Let us experiment

Aim To show that sound is a form of energy that can cause vibrations in objects.

Procedure:

1. Take a wide mouthed container, a cellophane or rubber sheet (such as that of a balloon) of size larger than its opening, a loud sound source (such as a metal plate and a beater) and some grains or particles (such as rice, semolina, salt, or chalk powder).
2. Stretch the sheet over the edges of the container tightly and fix it with tape or a rubber band (Fig.).
3. Sprinkle the grains evenly over the sheet, ensuring they are not clumped together.
4. Produce a loud sound near the bowl without touching it.

Observation:

1. When a loud sound is produced near the stretched sheet, the grains on it start moving or jumping.
2. The grains move even though the sound source is not touching the sheet.
3. The movement of grains increases when the loudness of sound increases.
4. Different sound sources produce different levels of vibration in the grains.
5. When the sound stops the grains also stop moving.
6. The sheet vibrates due to sound energy reaching it through air.

Conclusion: When the source of sound vibrates it transfers energy to the surrounding medium. When sound waves propagate through a medium, the vibration of particles of medium and their collisions with other particles result in transfer of energy. This proves that sound can produce motion without direct contact.