For most stable position of magnetic dipole in a uniform magnetic field the value of potential energy should be .......

Options

A. `- mB `
B. `0`
C. any value
D. `mB`

Answer

A

Explanation

Potential energy of dipole in magnetic field B,
`U= - overset(to)(m) .overset(to)(B) = - m B cos theta`
it becomes steady when `theta = 0^@` ,
`therefore U= -mB " "[because cos 0^(@) =1]`