TBQ - Sound through water — task. Physics CBSE Live product, Class 9 (2026-27).

Read the following case and answer the following questions:

A student fills a large bucket with water and takes two metal spoons. First, she taps the spoons together in air and listens to the sound. She then completely submerges both spoons in water, ensuring that they do not touch the sides or bottom of the bucket, and taps them together again.

1. Why is it important that the two spoons do not touch the sides or bottom of the bucket when they are tapped under water?

To prevent sound from entering the water.
To prevent water from becoming a solid medium.
To ensure that the observed sound is associated with the spoons and water rather than vibrations transmitted through the bucket.
To ensure that the spoons remain completely motionless.

2. The student hears the spoons when they are tapped in air and also when they are tapped under water. Which comparison best explains the significance of these two observations?

Water produces sound independently of the spoons.
Sound can travel through air but cannot travel through water.
Sound changes into a different type of wave when it enters water.
Sound can be transmitted through both air and water.

3. A student performs the activity correctly but cannot hear the sound when the spoons are tapped under water. Which conclusion would be the most scientifically appropriate?

It proves that the spoons cannot vibrate under water.
It proves that sound cannot propagate through liquids.
It proves that water is a vacuum.
The observation alone is insufficient to conclude that sound cannot travel through water; the experimental arrangement and hearing conditions should first be checked.

4. A student is swimming underwater and hears another swimmer striking two objects together nearby. Which concept from the spoon activity best explains this observation?

A liquid can act as a medium through which sound disturbances propagate.
The water becomes a source of light when disturbed.
Sound can travel only through the metal objects being struck.
Sound can travel through vacuum when the source is powerful enough.

8. TBQ - Sound through water

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