# What should be the output voltage for Virtual Ground to occur in Inverting OpAmps? If I give 1v as an input to this inverting opamp, the output should be -10v just to make the difference between the input terminals 0. But when I solve the circuit using KCL for 1 volt input I get 1000v as output ?

here is my calculation:

Va= Voltage at inverting terminal Vo = output voltage,

let Va = 0 (due to virtual ground at inverting terminal); (Vin-Va)/Rin = 10mAmps [that flows through input] [this 10 mAmps should also flow in the feedback path since no current goes into opamp], so 10mAmps * Rf = 1000V across feedback resistor

so Vo - Va = 1000volts

since Va = 0 Vo=1000V output when I should have -10v at output for virtual ground (0v at Va)

can someone clarify ?

Also why is that we have a voltage divider between Rin and Rf for voltages other than Virtual ground at say inverting OpAmp terminal?

thanks.

• Can you explain what exactly you want to say with the final question, "Also why is that we have a voltage divider between Rin and Rf for voltages other than Virtual ground at say inverting OpAmp terminal?" You want to understand the role of the voltage divider... or something else? Jan 23, 2015 at 9:16