Question

To determine the relation between frequency and length using sonometer wire

Answer 1

Materials Required:


A sonometer
A set of eight tuning forks
1/2 kg hanger
Seven 1/2 kg slotted weights
Rubber pad
Paper rider
Meter scale
Screw gauge.


The Procedure:


We'll place the sonometer on the table.
Test the pulley and if you experience any friction, make it frictionless by oiling it.
Place a suitable maximum weight in the hanger.
Move the wooden bridges P, outward to include maximum length of wire (AB) between them.
Take a tuning fork of least frequency from among the set, strike its prong with a rubber pad to make it vibrate. Bring the tuning fork near your ear.
Pluck the wire AB from the middle and leave it so that it vibrates.
Listen to the sound produced by the tuning fork and wire and judge which has less frequency.
Since the long wire may have less frequency, decrease its length by moving the bridges inward and check the frequencies again.
Go on decreasing the length till frequency of the vibrating wire AB becomes equal to the frequency of the tuning fork.
Put an inverted V shape paper rider R on the wire AB in its middle. Vibrate the tuning fork and touch the lower end of its handle with sonometer board. The wire AB vibrates due to resonance and paper rider falls.
Note the length of the wire AB between the edges of the two bridges and record it in 'length decreasing' column.
Bring the two bridges closer and then adjust the length of the wire by increasing it little by little till rider falls.
Note the length of the wire and record it in the 'length increasing' column.
Take the remaining five tuning forks, one by one, in order of increasing frequency and repeat steps 5 to 13.
Record your observations.