Two parallel conductors carrying current of 4.0 A and 10.0 A are placed 2.5 cm apart in vacuum. The force per unit length between them is -

The magnetic field at the centre of a current carrying circular loop of radius R is B₁. The magnetic field at a point on its axis at a distance R from the centre of the loop is B₂. Then the ratio (B₁ / B₂) is

A current carrying wire kept in a uniform magnetic field, will experience a maximum force when it is

A straight conducting rod of length l and mass m is suspended in a horizontal plane by a pair of flexible strings in a magnetic field of magnitude B. To remove the tension in the supporting strings, the magnitude of the current in the wire is