Write expression of magnetic field when solenoid has infinite length.

Write an expression for the magnetic field produced by an infinitely long straight wire carrying a current I, at a short perpendicular distance a from itself.

Using Ampere.s circuital law derive an expression for magnetic field due to infinitely long current carrying wire at a point at distance Yfrom it.

Derive an expression for the magnetic field intensity at a point on the equatorial line of the magnetic dipole.

Write characteristics of magnetic field lines.