JEE Main 2026 Physics question
A parallel plate air capacitor is connected to a battery. The plates are pulled apart at uniform speed v. If x is the separation between the plates at any instant, then the time rate of change of electrostatic energy of the capacitor is proportional to x^α, where α is .
Answer: (A)
Solution
U = ½CV² = ε₀AV²/(2x) ∝ 1/x. dU/dt = (dU/dx)(dx/dt) ∝ (1/x²)(v), so α = −2.