Question

Magnetic field due to current carrying wire of infinite length

Answer 1

Straight current carrying conductor of finite length –

Suppose a straight current carrying wire AB, carrying current i, lies in the plane of the paper as shown in the figure, P is a point at a perpendicular distance R from conductor, where magnetic field is to be determined.

Conductor

Answer 2

The magnitude of the field from a semi-infinite wire is half of that of an infinite wire ( look at direct integration of the Biot-Savart law): in z direction.