Materials Required
•A sonometer
•A set of tuning forks of known frequency
•0.5kg weight hanger
•Some 0.5kg slotted weights
•Rubber pad
•Paper rider
Real Lab Procedure
To find the relation between frequency and length
•Place the sonometer on the table.
•Make sure that the pulley is frictionless. If you feel any friction, oil them.
•Stretch the wire by placing a suitable maximum load on the weight hanger.
•Move the wooden bridges outward, so that the length of wire between the bridges is
maximum.
•Take a tuning fork of known frequency. Make it vibrate by strike its prong with a rubber
pad. Bring it near the ear.
•Pluck the sonometer wire and leave it to vibrate.
•Compare the sounds produced by tuning fork and sonometer wire. (Sound which has low
pitch has less frequency).
•Gently adjust the bridges for decreasing the length of wire, till the two sounds appear
alike.
•Put an inverted V shaped paper rider on the middle of the wire.
•Vibrate the tuning fork and touch the lower end of its handle with sonometer board. The
wire vibrates due to resonance and the paper rider falls.
•Measure the length of wire between the bridges using a meter scale. It is the resonant
length and record it in the ‘length decreasing’ column.
•Now, bring the bridges closer and then slowly increase the length of the wire till the
paper rider falls.
•Measure the length of wire and record it in ‘length increasing’ column.
•Repeat the above steps with tuning forks of other frequencies, and find resonant length
each time.
To find the relation between length and tension
•Select a tuning fork of known frequency
•Set the load in the weight hanger as maximum.
•Repeat the steps in the previous section to find out the resonant length.
