Question

The radius of a circular loop is 0.4m and the current is 12A. What is the magnitude of the magnetic field at the centre of the loop?

• A. $19.96\times {10}^{-8}T$
• B. $18.86\times {10}^{-6}T$
• C. $22.4\times {10}^{-6}T$
• D. $12.4\times {10}^{-8}T$

Answer 1

The correct option is B $18.86\times {10}^{-6}T$

$B=\frac{{\mu }_{0}I}{2r}$
${\mu }_0=4\pi \times {10}^{-7}Tm/A$
$I=12A$
$r=0.4m$
$B=\frac{4\pi \times {10}^{-7}\times 12}{2\times 0.4}=6\pi \times {10}^{-6}T$
$B=18.86\times {10}^{-6}T$