Question

The magnetic field at a distance of $2cm$ from the axis of a straight conductor carrying current is $12mT$. The current in the conductor is

• A. $12A$
• B. $1200A$
• C. $1210A$
• D. $125A$

Answer 1

Answer: (B)

$1200A$

Given: Magnetic field= $12mT$

Solution: The magnetic field due to the straight conductor carrying current is given by,

$B=\frac{{\mu }_{0}i}{2\pi r}$

where, i is the current,

r is the distance from the axis and

${\mu }_0$ is the permeability constant.

$i=\frac{2\pi rB}{{\mu }_0}$

$=\frac{2\pi \times 2\times {10}^{-2}\times 12\times {10}^{-3}}{4\pi \times {10}^{-7}}$

On solving we get,

$i=1200A$

Hence, the correct option is (B).