1. The problem statement, all variables and given/known data Calculate the input voltage to an Op-Amp circuit. The circuit is exactly an ideal non-inverting amplifier except the inputs have been switched in that the supply is connected to the inverting input and the middle of the potential divider is connected to the non-inverting input. 2. Relevant equations I would be completely comfortable solving this problem if it was not for the inputs having been switched. 3. The attempt at a solution Again, had the inputs not been switched I'd use:- Vin = R1/(R1 + R2) x Vout The best thing I can come up with is that the answer is the same but negative as opposed to positive. Any help much appreciated.