Two concentric circular loops of radius 5 cm and 15 cm are placed co-axially. Find e.m.f induced in the inner loop, if the current through the outer loop is changed at a rate of 10 A/ms. Assume the magnetic field on the inner loop to be uniform.
Answer & explanation
Correct answer: option 3
Magnetic field due to outer loop at its centre is $ \xi = \pi r^2 \times \frac{\mu_0 dI/dt}{2R} = \pi \times (5\times 10^{-2})^2 \frac{4\pi \times 10^{-7} \times 10^4}{2\times 15\times 10^{-2}} = 3.29\times 10^{-4}V$
The correct answer is Option (3) → $-3.29×10^{-4} V$