The current in a 4.70 mH inductor decays over time according to the following function, where t is in seconds.
I(t) = (.943A) e-(396 s-1) t)
(a) What is the induced emf across the inductor at t= 5.00 ms? (b) How long does it take the emf to drop below 1.25 mV?
The Attempt at a Solution
Since emf = -L(dI/dt) , I can take the derivative of the function above and plug in t=.005, right?
I' = (.943A) e-(396 s-1) t) (-1/396s)
Plug in t=.005 and I get I' = -.00238
emf = -L(dI/dt)
emf = -(.0047)(-.00238) = 1.119x10-5
I tried this answer but it was incorrect. What am I doing wrong?