The induced current in a coil declines linearly from 4 A to 0 in 0.1 s (graph shown). Coil resistance is 10 Ω. Find the total change in flux linkage in weber.
Physics · Mixed Chapter
JEE Mains

Question

The induced current in a coil declines linearly from 4 A to 0 in 0.1 s (graph shown). Coil resistance is 10 Ω. Find the total change in flux linkage in weber.

G1 Physics · Accepted Answer

Step 1 — Apply Faraday's induction law: Induced emf magnitude is |d(NΦ)/dt|, where NΦ denotes the flux linkage. The ohmic coil satisfies |emf| = Ri. Step 2 — Integrate over the given interval: |Δ(NΦ)| = R∫i dt. The current–time graph is a triangle with height 4 A and base 0.1 s. ∫i dt = ½(0.1)(4) = 0.20 A s. Step 3 — Multiply by resistance: |Δ(NΦ)| = 10 Ω×0.20 A s = 2 Wb. Answer: 2.