Question

Consider a straight, infinitely long, current carrying conductor lying on the z-axis. Which one of the following plots (in linear scale) qualitatively represents the dependence of $H_{\varphi }$ on r, where $H_{\varphi }$ is the magnitude of the azimuthal component of magnetic field outside the conductor and r is the radial distance from the conductor?

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

Ans : (c)

$H_{\varphi }=\frac{I}{2\pi r}{\hat{a}}_{\varphi }$

$\Rightarrow H_{\varphi }\propto \frac{1}{r}$
option (c) is satisfied.