With a standard rectangular bar magnet, the time period in the uniform magnetic field is `4 sec`. The bar magnet is cut parallel to its length into `4` equal pieces. The time period in the uniform magnetic field when the piece is used (in sec) (bar magnet breadth is small)

Options

A. `16`
B. `8`
C. `4`
D. `2`

Answer

C

Explanation

`T = 2pi sqrt((I)/(MB_(H)) )= 4`
`T^(1) = 2pisqrt((I // 4)/(M // 4.B_(H))) = 4`