In Melde's experiment the srting vibrates in 4 loops when a 50 g weight is placed on the pan of weight 15 g.How much weight must be added or removed to make the string vibrate in 6 loops ?

Options

A. 28 g
B. 35 g
C. 40 g
D. 42 g

Answer

B

Explanation

Equating frequency of vibration of the string in both cases we have
`P_(1)^(2)xxT_(1)=P_(2)^(2)xxT_(2)`
`implies4^(2)xx(50+13)=6^(2)xxT_(2)`
`therefore16xx63=36xxT_(2)`
or `T_(2)=(16xx63)/(36)`
=28 gram weight
`therefore` the weight that should be ltBrgt removed (63-28)=35g.