Question

The number of turns per unit length in a toroid is ${10}^3$ and current flowing in it is $\frac{1}{4\pi }A$, then the magnetic induction produced in it, is :

• A. ${10}^{4}T$
• B. $\frac{1}{4\pi }{10}^{4}T$
• C. ${10}^{-4}T$
• D. $\frac{1}{4\pi }{10}^{-4}T$

Answer 1

The correct option is C ${10}^{-4}T$

Given:

n = number of turns per $m={10}^3$

I= current $=\frac{1}{4\pi }$

Therefore magnetic field in toroid as $B=\mu nI$

$={10}^{-7}\times 4\pi \times {10}^3\times \frac{1}{4\pi }$

$B={10}^{-4}T$