Biot-Savart Law & Circular Coils question from MHT CET 2026 (14 May, Shift 2)

Answer: (b)

1. Equivalent current $I = qf = 100 \times 1.6 \times 10^{-19} \times 1 = 1.6 \times 10^{-17}\text{ A}$.
2. $B = \frac{\mu_0 I}{2r} = \frac{\mu_0 \times 1.6 \times 10^{-17}}{1.6} = \mu_0 \times 10^{-17}$
3. So the answer is (b) $\mu_0 10^{-17}$.