Smooth rails AB and CD are separated by distance ℓ and inclined at angle θ. A vertical magnetic field B exists. A conductor EF of mass m carries current i. For equilibrium:

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: i must flow from E to F l E; B: Bil = mg tan θ θ.