A charged 0.5 µF capacitor is discharged through a 2 Ω resistor and an ammeter by closing switch S at t = 0. At t = ln 2 µs, the ammeter reading becomes half its initial value. Find the resistance of the ammeter.

Question

G1 Physics · Accepted Answer

For discharge, I/I₀ = e ( − t / τ ) . e^(-t/τ). e ( − t / τ ) . Given I/I₀ = 1/2 at t = ln2 µs, τ = 1 µs. With C = 0.5 µF, total discharge resistance is τ/C = 2 Ω. Since the external resistor itself is 2 Ω, the ammeter resistance is 0. Hence A.