Question

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

• A. $4\times {10}^{-5}wb/m^2$
• B. $2\times {10}^{-5}wb/m^2$
• C. $3\times {10}^{-5}wb/m^2$
• D. $8\times {10}^{-5}wb/m^2$

Answer 1

Answer: (A)

Here: $i=20$ amp, $r=10cm=10\times {10}^{-2}m$ Intensity of magnetic field produced due to straight current carrying wire will be $B=\frac{{\mu }_0}{4\pi }\times \frac{2i}{r}$ $=\frac{{10}^{-7}\times 2\times 20}{0.1}=4\times {10}^{-5}wb/m^2$