Question

Magnetic field intensity $H$ at the centre of a circular loop of radius $r$ carrying current $I$ is

• A. $\frac {R}{I} $ oersted
• B. $\frac {2\pi I} {r}$ oersted
• C. $\frac {I} {2 \pi r}$ oersted
• D. $\frac {2\pi r}{I}$ oersted

Answer 1

Answer: (B)

$H=\frac{\mu_{0} I}{2 r}=\frac{\mu_{0}}{4 \pi} \times \frac{2 \pi I}{r}$
In emu system $\frac{\mu_{0}}{4 \pi}=1$
So, $H=\frac{2 \pi I}{r}$ oersted