Write the expression for the magnitude of force per unit length between two infinitely long parallel straight conductors.

Derive an expression of Force between two infinitely long parallel current carrying conductors.

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.

A horizontal wire AB of length 'l' and mass 'm' carries a steady current I_1 , free to move in vertical plane is in equilibrium at a heigh of 'h' over another parallel long wire CD carrying a steady current I_2 , which is fixed in a horizontal plane as shown. Derive the expression for the force acting per unit length on the wire AB and write the condition for which wire AB is in equilibrium.

Prove that the parallel conductors of infinite length, carry current in the same direction, attravt each other. Deduce the expressions for the force per unit length experienced by each conductor.

Write expression of magnetic field when solenoid has infinite length.