mutual induction problem..

https://i28.tinypic.com/ot42gi.jpg

in normal induction finding question
we need to have how a current changes over some period
of time

and emf.

but here i dont have that
i only have emf =-3.2
in t=0.8 i can find a certain current
and in t=0 i can find a certain current.(using the given formula )
i can put them in the formula and get M
[latex]
\epsilon=-M\frac{I(0.8)-I(0)}{0.8-0}
[/latex]
is it ok??

because they presented a much more complicated current.

is it ok??

Click to expand...

No!!! The frequency is 60 Hz. A delta t of .8s is way too large to approximate the derivative. Just take the derivative analytically. It's not hard.

in what cases i ca do my presented method?

thanks i figured it out