Question

Straight wire of indefinite length (transient) passed by an electric current of 5.0 A. The magnetic field generated around this conductor at point M is 50 μT. Thus the distance from the conductor to point M is:
A. 2π cm

B. 0.2π cm

C. 2.0 cm

D. 0.20 cm​

Answer 1

Answer:

C. 2.0 cm

Explanation:

The magnetic field around the wire at point M is given by Biot-Savart Law:

$B = \frac{\mu_o I}{2\pi R}$

where,

B = Magnetic field = 50 μT = 5 x 10⁻⁵ T

I = current = 5 A

μ₀ = permeability of free space = 4π x 10⁻⁷ N/A²

R = distance of point M from wire = ?

Therefore,

$5\ x\ 10^{-5}\ T = \frac{(4\pi\ x\ 10^{-7}\ N/A^2)(5\ A)}{2\pi R}\\\\R = \frac{(2\ x\ 10^{-7}\ N/A^2)(5\ A)}{5\ x\ 10^{-5}\ T}$

R = 0.02 m = 2 cm

Hence, the correct option is:

C. 2.0 cm