Question

A straight conductor of length $32\, cm$ carries a current of $30\, A$. Magnetic induction at a point in air at a perpendicular distance of $12\, cm$ from the mid-point of the conductor is

• A. 0.2 G
• B. 0.3 G
• C. 0.4 G
• D. 0.5 G

Answer 1

Answer: (C)

$\beta=\frac{\mu_{0} I}{4 \pi r}\left(\sin \theta_{1}+\sin \theta_{2}\right)$
$=\frac{10^{-7} \times 30}{12 \times 10^{-2}}\left(2 \times \frac{16}{20}\right)$
$=4 \times 10^{-5}\, T$
$=0.4 \times 10^{-4}\, T$
$=0.4\, G$