A uniform magnetic field exists inside a circular region of radius R and decreases at a constant rate. A concentric charged wooden ring of radius 2R and an uncharged copper ring of radius 3R are placed on a frictionless surface. Select the correct alternatives.

Question

G1 Physics · Accepted Answer

Magnetic flux is Φ=∫B⃗·dA⃗ and induced emf is ε=-dΦ/dt. Apply Lenz’s law for direction and I=ε/R when the circuit is resistive. This gives A: There is no induced current in wooden ring; B: Induced electric field in wooden ring is more in magnitude then copper ring; D: Wooden ring will start rotating.