Question

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

• A. $4\text{x 1}{\text{0}}^{-5}Wb/m^2$
• B. $\text{9 x 1}{\text{0}}^{-5}Wb/m^2$
• C. $8\text{x 1}{\text{0}}^{-5}Wb/m^2$
• D. $6\text{x 1}{\text{0}}^{-5}Wb/m^2$

Answer 1

The correct option is A $4\text{x 1}{\text{0}}^{-5}Wb/m^2$

The magnetic field at a distance from the wire is:

$B=\frac{{\mu }_0}{4\pi }.\frac{2i}{r}$

$={10}^{-7}\times \frac{2\times 20}{10\times {10}^{-2}}$

$=4\times {10}^{-5}Wb/m^2$