What is magnetic dipole moment for a coil ? Write its SI unit and dimensional formula.

Explanation

1. The product of current flowing from coil and area vector of that coil is known as magnetic dipole moment.
2. If I current flow through coil and A be the area of this coil, then magnetic dipole moment is given by,
`vecm=IvecA`
3. If N number of turns, then dipole moment is define as,
`vecm=NIvecA`
4. SI unit of dipole moment is `Am^(2)` and its dimensional formula is given by `[M^(0)L^(2)T^(0)A^(1)]`.
5. `vectau=vecmxxvecB`
`thereforetau=mBsintheta`
`therefore" If "vecmandvecB` both are parallel `(theta=0^(@))` or anti parallel `(theta=180^(@))` to each other than torque will be zero and it is stable equilibrium.
6. If `theta=0^(@)`, then coil is in stable equilibrium.
7. When `theta=180^(@)` then it is in maximum unstable equilibrium because at any small rotation of the coil produces a torque which brings it back to its original position.