The magnet of a vibration magnetometer is heated so as to reduce its magnetic moment by `19%`. By doing this the period time of the magnetometer will

Options

A. increase by `19%`
B. decrease by `19%`
C. increase by `11%`
D. decrease by `11%`

Answer

C

Explanation

`T=2pisqrt(I/(MB)) and T^(')=2pisqrt((Ixx100)/(81MB))implies T^(')=10/9T`
Percentage increase `=(10/9-1)/1xx100=1/9xx100~~11`.