Question

what will happen to the frequency of a sonometer wire if the weight stretching the sonometer wire is dipped in water

Answer 1

We know that the frequency of the sonometer wire is directly proportional to square root of tension caused by the weight.

f ∝ √T

If the weight is immersed in water then it will experience a buoyant force in upward direction causing the net weight to be decreased.

Thus new tension will be,

T = W- U

where U is the buoyant force.

Hence the new frequency will be

f ∝ √(W-U)

Hence when the weight is immersed in water it will cause a decrease in the frequency.