Im trying to understand this basic circuit from a book.
The book said: "The analysis is simple, if you remember your golden rules:
(The golden rules:
I. The output attempts to do whatever is necessary to make the voltage difference between the inputs zero.
- Point B is at ground, so rule I implies that point A is also.
This means that (a) the voltage across R2 is VOut and (b) the voltage across R1 is Vin"
So, using rule 11, we have In other words, voltage gain = Vout/Vin = -R2/R1
I cant understand why voltage across R1 is Vin and in R2 is Vout