1. The problem statement, all variables and given/known data Can anyone tell me what input impedance is? The context is "...these two solenoids act as a transformer. An AC voltage Vexp[jwt] is placed across the first and a resistor R across the second. Show that the input impedance of the first solenoid is equivalent to a circuit consisting of an inductance L1 in parallel with a resistor R'. Find R'." L1 is the self-inductance of the first solenoid btw. 2. Relevant equations 3. The attempt at a solution I thought the impedance of the first solenoid is just jwL, but apparently input impedance is different somehow?