Question

The magnetic induction due to a straight current-carrying conductor of infinite length at a distance $r$ from it proportional to

• A. $i^{-1}$
• B. $i$
• C. $i^{-2}$
• D. $i^2$

Answer 1

Answer: (B)

$i$

Magnetic field for an infinite wire at a distance $r$ from the wire: $B=\frac{{\mu }_{0}i}{2\pi r}$
$\therefore B$ is proportional to $i$.