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

• $R_1 = R_3 = R_4 = R$
• $R_2 = 2 \cdot R$
• $U_I$ comes from a low-resistance source
• $U_O$ is due to a high-resistance consumer

Exercises

1. Enter the voltage gain $A_V$ 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 justification how
   1. a short circuit of the two OPV inputs must be taken into account,
   2. Resistances are to be considered when doing this:
      1. with a terminal („on one side“) are directly and exclusively on an OPV input,
      2. with one terminal each are directly connected to an OPV input.
4. In which circuits do resistors $R_3$ and $R_4$ represent an unloaded voltage divider?

In order 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.