A long solenoid ‘S’ has ‘n’ turns per meter, with diameter ‘a’. At the centre of this coil we place a smaller coil of ‘N’ turns and diameter ‘b’ (where b < a). If the current in the solenoid increases linearly, with time, what is the induced emf appearing in the smaller coil. Plot graph showing nature of variation in emf, if current varies as a function of `mt^2 + C`.

A long solenoid of length l, crosssectional area A and having N_1 turns(primary coil), has a small coil of N_2 turns (secondary coil) wound about its centre. Determine the Mutual inductance (M) of the two coils.

A long wire carries a steady current . It is bent into a circle of one turn and the magnetic field at the centre of the coil is B . It is then bent into a circular loop of n turns. The magnetic field at the centre of the coil will be

A long solenoid of length L has a mean diameter D . It has n layers of windings of N turns each. If it carries a current ‘i’ the magnetic field at its centre will be

A long solenoid consisting of 1.5xx10^3 turns//m has an area of cross-section of 25 cm^2 . A coil C, consisting of 150 turns (N_c) is wound tightly around the centre of the solenoid. Calculate for a current of 3.0 A in the solenoid (a) the magnetic flux density at the centre of the solenoid, (b) the flux linkage in the coil C, (c) the average emf induced in coil C if the current in the solenoid is reversed in direction in a time of 0.5 s. (mu0=4pixx10^-7 T.m//A) .

A 50 m long solenoid has 500 turns and produces a magnetic field of 2.5 xx 10^-4 T at its centre. Find the current in the solenoid.

A long solenoid carrying a current produces a magnetic field B along the axis. If the number of turns per cm is tripled and the current is halved, then the new value of the magnetic field will be

A current of 10A passes through a coil having 5 turns and produces a magnetic field of magnitude. 5 xx 10^-4T at th e centre of the coil. Calculate the diameter of the coil.