# Inverting Opamp Question

#### rkrutz

Joined Dec 2, 2009
29
Hello,

I have a question about solving for Rin. Normally when we have been given a problem to solve for Rin there is a resistor after it. In this case since there is no resistor I have assumed that Rin would be infinite, would this still be true since A is a finite gain? Since when I do the calculation A=Rf/Rin having A=10000 ohms and Rf 10k ohms so that would say Rin is 1 ohm, which I feel is too small.