1. Derive an equation to find the induced EMF on an inner solenoid by a changing current on an outer solenoid. 2. Relevant equations We're given the equation EoRMS=(No*Ai*(2*pi*f)*(permeability constant)*IiRMS)/Li for the induced EMF on the outer solenoid by a changing current in the inner. I need an equation to replace this for when it's the other way around. 3. The attempt at a solution I have no idea where to even begin, I just need a hint as to how I should start.