The problem I keep running into with the first equation you listed is that I do not know what the radius of the solenoid is, and as a result I am unable to determine the surface area of the solenoid.
Homework Statement
A solenoid inductor has an emf of 0.20 V when the current through it changes at the rate 10.0 A/s. A steady current of 0.10 A produces a flux of 5.0 microWb per turn.
The number of loops in the solenoid is the value which needs to be found.
Homework Equations...