JEE Main 2026 Physics question
A metal rod of length L rotates about one end at origin with a uniform angular velocity ω. The magnetic field radially falls off as B(r)=B₀e^(−λr); λ being a positive constant. The emf induced (neglecting the centripetal force on electrons in the rod) is:
Answer: (A)
Solution
EMF=∫₀^L ωrB(r)dr=ωB₀∫₀^L re^(−λr)dr. Integrating by parts gives B₀ω[1/λ²−e^(−λL)(1/λ²+L/λ)].