Question

A circular loop of one turn carries a current of 5.00 A. If the magnetic field B at the centre is 0.200 mT, find the radius of the loop.

Answer 1

Given:
No. of turns, n = 1
Magnitude of current, i = 5.00 A
Now, let the radius of the loop be r.
Thus, the magnetic field at the centre due to the current in the loop is given by

\[B = \frac{\mu_0 i}{2r}\]

\[\Rightarrow 0 . 2 \times {10}^{- 3} = \frac{4\pi \times {10}^{- 7} \times 5}{2r}\]
\[ \Rightarrow r = 1 . 57 \times {10}^{- 2} \] m = 1 . 57 cm