A straight section `PQ` of a circuit lise along the `X`-axis from `x=-a/2` to `x=a/2` and carriers a steady current `i`. The magnetic field due to the section `PQ` at a point `X=+a` will be

Options

A. proportional to l/a
B. zero
C. proportional to a
D. proportional to `a^(2)`

Answer

B

Explanation

The point R is at a distance x=a. Hence the magnetic field at P due to the section PQ of the circuit will be zero because the magnetic field at a point on the axis of a current carrying is zero.