A magnetic dipole of magnetic moment `6 xx 10^(-2)A m^(2)` and moment of inertia `12 xx 10^(-6) kg m^(2)` performs oscillations in a magnetic field of `2 xx 10^(-2)T`. The time taken by the dipole to complete 20 oscillations is (`pi = 3`)

Options

A. 6s
B. 12s
C. 36s
D. 18s

Answer

B

Explanation

The magnetic field B is given as `T=2 pi sqrt((1)/(mB))`
Here, `B=2 xx 10^(-2) T`, `I=12 xx 10^(-6) kg m^(2)` ,
`m=6 xx 10^(-2) A m^(2)`
Putting these values we get,
`T=2pi sqrt((12 xx 10^(-6))/(6 xx 10^(-2) xx 2 xx 10^(-2)))=(2 xx 3.14)/(10)=0.6 s`
`"The time taken by the dipole to complete 20 oscillations" =0.6 xx 20=12 s`