Question

An electric wire in the wall of a building carries a DC current of 25 A vertically upward. What is the magnetic field due to

this current at a point which is 10 cm to the right of the wire?​

Answer 1

see diagram, here it is given that An electric wire in the wall of a building carries a DC current of 25 A vertically upward. let us consider a point P which is located at 10cm from electrical wire.

now, magnetic field at P due to electrical wire , B = $\frac{\mu_0i}{2\pi r}$

here, $\mu_0$ = 4π × 10^-7 N/A²

i = 25A and r = 10cm = 0.1m

so, B = 4π × 10^-7 × 25/(2π × 0.1)

= 2 × 10^-7 × 25/(0.1)

= 20 × 25 × 10^-7

= 5 × 10^-5 T

hence, magnet field due to electric wire at P is 5 × 10^-5 T