Two long coaxial solenoids of radius R and 2R have equal number of turns per unit length. They carry time-varying currents. `i_(1) = 2 kt and i_(2) = kt` respectively, in the same direction. A point charge released between the solenoids at a distance r, is seen to move along a circular path. Then the value of r is

A long solenoid has a radius a and number of turns per unit length is n . If it carries a current i, then the magnetic field on its axis is directly proportional to

Two long co-axial solenoids have radii, and number of turns per unit length equal to r_(1), r_(2) and n_(1), n_(2) respectively where suffix 1 refers to the outer solenoid and 2 refers to the inner solenoid. Length of both is l. The current in the outer solenoid is made to grow as I_(1) = kt where t is time. Resistance of the wire used in inner solenoid is R. Write the current induced in the inner solenoid assuming that it is shorted.

Two coaxial circular loops of raadii r_(1) and r_(2) are separated by a distance x and carry currents i_(1) and i_(2) respectively. Calculate the mutual inductance. What is the force between the loops ?

There are two long co-axial solenoids of same length l. The inner and other coils have redii r_(1) and r_(2) and number of turns per unti length n_(1) and n_(2) respectively .The reatio of mutual inductance to the self - inductance of the inner- coil is :

Two coaxil solenoids 1 and 2 of the same length are set so that one is inside the other. The number of turns per unit length are n_(1) and n_(2) . The current i_(1) and i_(2) are flowing in opposite directions. The magnetic field inside the inner coil is zero. This is possible when

Two parallel coaxial circular coils of equal radius R and equal number of turns N carry equal currents I in the same direction and are separated by a distance 2R . Find the magnitude and direction of the net magnetic field produced at the mid-point of the line joining their centres.

The current in a long solenoid of radius R and having n turns per unit length is given by i= i_0 sin omega t . A coil having N turns is wound around it near the centre. Find (a) the induced emf in the coil and (b) the mutual inductance between the solenoid and the coil.

Two coaxial solenoids having same number of turns per unit length n, and radius R and 2R respectively have no current initially. Current in both grows uniformly such that current in the inner one is twice that of the outer one, at any instant of time in the same direction. Current in outer one at time t is Kt then induced electric field at a distance r from axis is (R lt r lt 2R) .