An RL circuit with a DC source has time constant τ and current i(t). Which expression is correct for i(t) after t seconds?

• A. i(t) = (V/R) (1 - e^{-t/τ})
• B. i(t) = (V/R) e^{-t/τ}
• C. i(t) = V/R
• D. i(t) = (V/R) (1 - e^{t/τ})

Answer: (A)