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š” A pure note
A tuning fork gives an almost single, clean frequency — which is why scientists love it for sound experiments.
What is a tuning fork?
- A U-shaped metal bar with a stem, usually of steel or aluminium.
- The two sides of the ‘U’ are called prongs (or tines).
- Struck on a soft pad, the prongs vibrate and produce a nearly single-frequency sound.
In this Activity, we will explore how a vibrating tuning fork produces sound and disturbs a water surface.
- Strike one prong gently against a rubber pad (never a hard surface) and bring it near your ear.
- Gently touch a water surface with a vibrating prong (Fig. 10.4c).
- Repeat, bringing the prongs near your ear in different orientations.
What we observe
You hear the sound, and ripples form on the water — showing the prongs are indeed
vibrating
. Sound is produced by vibrating objects.
āøā¶ Pause and Ponder
- 1. Ways to produce sound: plucking a string, striking a metal object, blowing air in a pipe, tapping a membrane — all involve vibration.
- 2. Instruments and their vibrating parts: sitar/veena (strings), tabla/drum (membrane), bansuri/flute (air column), taal (metal body).
š§µ Threads of Curiosity
What if your name were a tune instead of a word? In Kongthong, a village near Shillong in Meghalaya — the ‘Whistling Village’ — every person has a tune-name that can be sung or whistled. This tradition, Jingrwai Iawbei , begins at birth when a mother composes a lullaby-like tune for her child.
Important Definitions
- Tuning fork — a U-shaped metal bar that vibrates to give a nearly single-frequency sound.
- Prongs — the two arms of a tuning fork that vibrate when it is struck.
