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. protportional to `a`
B. proportional to `I//a`
C. proportional to `a^(2)`
D. zero

Answer

4

Explanation

`bar(dl)xxbar(r)=0`