Below you will find circuits with an ideal operational amplifier, which are similar to the non-inverting amplifier and whose voltage gain $A_V$ must be determined.

Assumptions

• $R_1 = R_3 = R_4 = R$
• $R_2 = 2 \cdot R$
• $U_\rm I$ comes from a low-resistance source
• $U_\rm O$ is due to a high-resistance consumer

Exercises

1. Enter the voltage gain $A_\rm V$ for each circuit. A detailed calculation as before is not necessary.
2. For Figure 7, indicate how the voltage gain can be determined.
3. Generalize with the following justifications:
   1. How has a short circuit of the two OPV inputs must be taken into account?
   2. How do resistances have to be considered in the following cases:
      1. with one terminal (so „one connector“) directly and exclusively on an OPV input,
      2. with both terminals each directly connected to an OPV input.
4. In which circuits do resistors $R_3$ and $R_4$ represent an unloaded voltage divider?

To approach the problems, you should try to use the knowledge from the inverting amplifier. It can be useful to simulate the circuits via Falstad-Circuit or Tina TI. In the first two circuits, tips can be seen under the illustration as support.

Important: As always in your studies, you should try to generalize the knowledge gained from the task.