In order to have a current in a long wire, it should be
connected to a battery or some such device. Can we
obtain the magnetic field due to a straight, long wire by
using Ampere's law without mentioning this other part of the circuit?

In using Ampere's law,to find the magnetic field inside a straight long soleniod the loop that is taken is

A long wire having a semi-circular loop of radius r carries a current I, as shown in Fig. Find the magnetic field due to entire wire.

Consider a 10-cm long piece of a wire which carries a current of 10A . Find the magnitude of the magnetic field due to the piece at a point which makes an equilateral triangle with the ends of the piece.

Statement-1: Ampere's law cannot be used determine magnetic field due a current carrying wire of finite length Statement-2: Ampere's law is not valid for wires finite length

A very long bar magnet is placed with its north pole coinciding with the centre of a circular loop carrying an electric current. i . The magnetic field due to the magnet at a point on the periphery of the wire is B . The radius of the loop is a . The force on the wire is

The figure shows a circular loop of radius a with two long parallel wires (numbered 1 and 2) all in the plane of the paper . The distance of each wire from the centre of the loop is d . The loop and the wire are carrying the same current I . The current in the loop is in the counterclockwise direction if seen from above. (q) The magnetic fields(B) at P due to the currents in the wires are in opposite directions. (r) There is no magnetic field at P . (s) The wires repel each other. (4) When d~~a but wires are not touching the loop , it is found that the net magnetic field on the axis of the loop at a height h above the loop is zero. In that case

The strength of the magnetic field at a point r near a long straight current carrying wire is B . The field at a distance r/2 will be

The strength of the magnetic field at a point r near a long straight current carrying wire is B . The field at a distance r/2 will be

A part of a long wire carrying a current i is bent into a circle of radius r as shown in figure. The net magnetic field at the centre O of the circular loop is

A part of a long wire carrying a current i is bent into a circle of radius r as shown in figure. The net magnetic field at the centre O of the circular loop is :