Question

A wire placed along the north-south direction carries a current of 8 A from south to north. Find the magnetic field due to a 1 cm piece of wire at a point 200 cm north-east from the piece.

(a) 14 × 10^-9 T

(b) 1004 × 10^-9 T

(c) 204.4 × 10^-9 T

(d) 1.4 × 10^-9 T

This question was posed to me in an interview for internship.

Question is from Magnetic Field due to a Current Element & Biot-Savart Law topic in chapter Moving Charges and Magnetism of Physics – Class 12

Answer 1

The correct option is (d) 1.4 × 10^-9 T

The best I can explain: dB = \(\frac {(\mu_0 I dl sin (\theta))}{(4\pi r^2)}\).

dB = \(\frac {(4 \pi \, \times \,  10^{-7} \, \times \,  8 \, \times \,  1 \, \times \,  10^{-2} \, \times \,  sin 45^o}{(4 \pi \, \times \,  22)}\)

dB = 1.4 × 10^-9 T.