I would like to verify these answers please.. What is the inductance of a series RL circuit in which R=1.0 K ohms if the current increases to 1/3 of it's final value in 30 Ms (M is the greek symbol Mu). Is the answer 30 (none of these) or is it 74mH?? I calculated 74mH i(t) = I (1-1/e^t/τ) given i(t) = 1/3*I and t =30uS and τ =L/R so,,substitutin these values we get t/τ = 0.41 30*10^-6 / τ = 0.41 τ ˜ 74 μ sec L/R ˜ 74usec R = 1K so,,L ˜74mH The choices for answers are. 1.) 49 2.) none of these 3.) 99 4.)74 5.) 62 thankyou!