Question

The magnetic field at a perpendicular distance of $2 \,cm$ from an infinite straight current carrying conductor is $2 \times 10^{-6} T$. The current in the wire is

• A. 0.1 A
• B. 0.2 A
• C. 0.4 A
• D. 0.8 A

Answer 1

Answer: (B)

The magnetic field due to a infinite straight curren carrying conductor at a perpendicular distance $r$ from it is given by
$B=\frac{\mu_{0}}{4 \pi} \frac{2 I}{r}$
Substituting the given values, we get
$2 \times 10^{-6}=\frac{10^{-7} \times 2 \times I}{0.02}$,
$ I=\frac{2 \times 10^{-6} \times 0.02}{10^{-7} \times 2}=0.2 A$