Sonometer is device used to measurethe frequency of tunning fork. A wire is stretched by appling tension at one end and fixing the other end to a screw that is provided. If ithe string is subjected to a distrubance it would vibrate with a certain frequency.

For sonometer experiment, the apparatus consist of a wooden box which is hallow and has holes on the sides for free vibrations of air inside. A thin wire of whose linear density is known is stretched over the bridges by means of hanging weights over a pulley with other end fixed. By changing the distance between the wooden bridges the length of the vibrating column can be changed. A small paper rider is placed on the string between the bridges. A standard tuning fork is struck with a rubber hammer and the stem of the fork is kept on the box. Now by moving the distance of the bridges, the length of the vibrating column can be adjusted until the frequency of vibrations of the string is equal to the frequency of tuning fork. At resonance (frequencies equal) the paper rider is thrown off the wire.

Verification of law:

The tension in the wire is kept constant by keeping the weights that are hung over the pulley are unchanged. A tuning forkof known frequency is excited with rubber hammer and is placed on the sonometer. The bridges are adjusted until the paper rider is thrown off indicating the condition of resonance. The corresponding length between the bridges is noted. By changing the frequency of the tuning the experiment is repeated and the corresponding value of the length of the vibrating column is noted. If f is the frequency and L is the length of the vibrating column then

f₁L₁= f₂L₂= constant

Sonometer is device used to measurethe frequency of tunning fork. A wire is stretched by appling tension
at one end and fixing the other end to a screw that is provided. If ithe
string is subjected to a distrubance it would vibrate with a certain
frequency.
For sonometer experiment, the
apparatus consist of a wooden box which is hallow and has holes on the
sides for free vibrations of air inside. A thin wire of whose linear
density is known is stretched over the bridges by means of hanging
weights over a pulley with other end fixed. By changing the distance
between the wooden bridges the
length of the vibrating column can be changed. A small paper rider is
placed on the string between the bridges. A standard tuning fork is
struck with a rubber hammer and the stem of the fork is kept on the box.
Now by moving the distance of the bridges, the length of the vibrating
column can be adjusted until the frequency of vibrations of the string
is equal to the frequency of tuning fork. At resonance (frequencies
equal) the paper rider is thrown off the wire.
proof
Verification of law:

The tension in the wire is kept constant by keeping the weights that are hung over the pulley are unchanged. A tuning forkof known frequency is excited with rubber hammer and is placed on the
sonometer. The bridges are adjusted until the paper rider is thrown off
indicating the condition of resonance. The corresponding length between
the bridges is noted. By changing the frequency of the tuning the
experiment is repeated and the corresponding value of the length of the
vibrating column is noted. If f is the frequency and L is the length of
the vibrating column then
f1L1= f2L2= constant
Thanks & Regards
Rinkoo Gupta
AskIITians Fcaulty