A circular loop of area \(1\) cm², carrying a current of \(10\) A, is placed in a magnetic field of \(0.1\) T perpendicular to the plane of the loop. The torque on the loop due to the magnetic field is:
1. zero
2. \(10^{-4}\) N-m
3. \(10^{-2}\) N-m
4. \(1\) N-m

A current-carrying straight wire is kept along the axis of a circular loop carrying a current. The straight wire

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 

1.  very nearly 2πaiB perpendicular to the plane of the wire 

2.  2πaiB in the plane of the wire 

3.  πaiB along the magnet

4.  zero.