medium difficulty8 min

Production of Sound

Sound is produced when an object vibrates and sets the surrounding medium into vibration.

In one line: No vibration, no sound.

Understand it

A vibrating object moves to and fro very rapidly. This motion pushes and pulls nearby air particles, creating disturbances that our ears can detect as sound. A tuning fork, drum skin, stretched rubber band, and vocal cords all produce sound because some part of them vibrates.

Example

When a struck tuning fork is touched to water, the water splashes because the prongs are vibrating rapidly.

Rule to remember

Rule: A vibrating body is necessary for production of sound.

Greater vibration energy generally gives louder sound, but the basic cause remains vibration.

See it worked out

Follow the example line by line, then use the same method on new questions.

Worked example

A student strikes a tuning fork and then holds it near the ear.

1Sound is heard because the fork's prongs vibrate and transfer disturbance to air particles.
2When the prongs stop vibrating, sound also stops.

Method you can reuse

1Identify the object producing sound.
2Find the part that vibrates.
3State that vibration disturbs air particles.
4Connect this disturbance to hearing sound.

Sketch it in your answer

Show a tuning fork with prongs moving inward and outward, and label vibrating prongs and surrounding air disturbance.

Check yourself

Answer the question in your head before opening the answer.

Try it yourself

Why does a stretched rubber band produce sound when it is plucked?

Think first, then show answer

A stretched rubber band produces sound because it vibrates rapidly after being plucked and makes the surrounding air particles vibrate.

Common wrong answer

Sound is produced because the object moves from one place to another.

Why it loses marks: Vibration is repeated to-and-fro motion about a mean position, not overall displacement.

Don't mix this up

Students often say sound is produced by force alone. Force may start the vibration, but continuous vibration is the immediate cause of sound.

Exam tip

In observation-based answers, always mention the vibrating part, such as prongs of tuning fork, drum membrane, or vocal cords.