Question

$20$ ampere current is flowing in a long straight wire. The intensity of magnetic field at a distance $10\, cm$ from the wire will be

• A. $2 \times 10^{-5} Wb / m ^{2}$
• B. $9 \times 10^{-5} Wb / m ^{2}$
• C. $4 \times 10^{-5} Wb / m ^{2}$
• D. $6 \times 10^{-5} Wb / m ^{2}$

Answer 1

Answer: (C)

Here: $i=20\, A,\, r=10\, cm =01\, m$
Intensity of magnetic field produced due to straight current carrying wire is
$B =\frac{\mu_{0}}{4 \pi} \times \frac{2 i}{r}$
$=10^{-7} \times \frac{2 \times 20}{0.1}$
$=4 \times 10^{-5} Wb / m ^{2}$