A coil having `N` turns is would tightly in the form of a spiral with inner and outer radii a and `b` respectively. When a current `I` passes through the coil, the magnetic field at the centre is.

A coil having N turns is wound tightly in the form of a spiral with inner and outer radii a and b respectively. A current I passes through the coil. The magnetic moment of the spriral is

A coil having N turns is wound tightly in the form of a spiral with inner and outer radii 'a' and 'b' respectively. Find the magnetic field at centre, when a current I passes through coil:

A toroidal coil has 3000 turns. The inner and outer radii are 10 cm and 12 cm respectively. If current flowing is 5 A, then the magnetic field inside the toroid will be

A long insulated copper wire is closely wound as a spiral of N turns. The spiral has inner radius a and outer radius b . The spiral lies in the xy -plane and a steady current I flows through the wire. The z -component of the magetic field at the centre of the spiral is

A flat coil, in the shape of a spiral, has a large number of turns N. The turns are wound tightly and the inner and outer radii of the coil are a and b respectively. A uniform external magnetic field (B) is applied perpendicular to the plane of the coil. Find the emf induced in the coil when the field is made to change at a rate (dB)/(dt) .

A current passing through a circular coil of two turns produces a magnetic field B as its centr. The coil is then rewound so as to have four turns and the same current is passed through it. The magnetic field at its centre now is

A circular coil carrying a certain, current produces a magnetic field B_(0) at its centre. The coil is now rewound so a to have 3 turns and the same currents is passed through it. The new magnetic field at the centre is