Question

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

The correct option is B $\frac{2\pi I}{r}$ oersted

$H=\frac{{\mu }_{0}I}{2r}=\frac{{\mu }_0}{4\pi }\times \frac{2\pi I}{r}$
In emu system $\frac{{\mu }_0}{4\pi }=1$
So, $H=\frac{2\pi I}{r}$ oersted