Electromagnetic induction graph of E versus I

[delsoo]

Homework Statement

for this question, i only know that E=-L dI/dt... the ans is C , can anyone explain how to get C?

Homework Equations

The Attempt at a Solution

 

[BvU]

Your "I only know" expression does not apply. I is in the big coil, not in the little rectangular one.

"Carrying a variable I" here means they are able to set the current to a number of values. (*) You may assume dI/dt = 0.

(*) So what do they vary in this way ? Aha!