Figure $19

Question

Figure $19 < 2$
-If the inputs are -7.1 V and 12 V in Figure 19-2(a),W hat is the output voltage?
A)4.9V 
B)-4.9V 
C)19.1V 
D)-19.1V

Quizplus · Accepted Answer

From Figure 19-2(a), we can see that the op-amp is configured as an inverting amplifier. The output voltage is given by:
Vout = -(Rf/Rin) Vin
where Vin is the input voltage and Rf/Rin is the ratio of the feedback and input resistors. 
Given inputs are -7.1 V and 12 V, and assuming Rf = 10 kΩ and Rin = 2 kΩ, we get:
Vout = -(10/2) (-7.1+12) = -4.9 V (since the output voltage is negative, answer B is correct)

Figure 19<219 < 219<2 -If the Inputs Are -7

Figure $19 < 2$ -If the Inputs Are -7