Question:

A coil of circular cross-section having 1000 turns and 4 cm² face area is placed with its axis parallel to a magnetic field which decreases by 10⁻² Wb/m² in 0.01 s. The e.m.f. induced in the coil is:

400mV

0.4mV

200mV

4mV

Answer is D
From Faraday's law, we know that
E=−ndΦ/dt
E=−nAdB/dt cosθ=1
E=1000 × 4 × 10⁻⁴ × 10⁻²/0.01 = 400mV