Question

A straight wire of diameter 0.5 mm, carrying a current of 1A is replaced by another wire of 1mm diameter carrying the same current. The strength of magnetic field far away is

Answer 1

Magnetic Field created by a Current-Carrying Conductor:

1. When we move further away from a current carrying wire, the magnetic field decreases with the distance.
2. Ampere’s law is the equation that gives the magnetic field at a distance r from a long conductor carrying current $I$. It is written as $B=\frac{{\mu }_{o}I}{2\pi r}$.
3. So B does not depend on the diameter of the wire.
4. Since the current in both the wires is the same, therefore there is no change in the strength of the magnetic field.

Hence, B is unchanged.