Question
What voltage gain can be expected from the circuit in Figure E7-3 when R1 is 10 ohms and RF is 470 ohms?
Answer Options
- A) 0.21
- B) 4700
- C) 47
- D) 24
Correct Answer: C
Explanation
Figure E7-3 shows an inverting operational amplifier circuit, which is one of the most common applications for op-amps. The voltage gain of an ideal inverting amplifier is set exclusively by the ratio of the feedback resistor (R_F) to the input resistor (R_1).
The voltage gain (A_V) is calculated using the formula A_V = -R_F / R_1. Substituting the values, the absolute voltage gain is |A_V| = 470 \Omega / 10 \Omega = \mathbf{47}. The negative sign only indicates that the output signal is 180^\circ out of phase with the input signal, but the magnitude of the gain is 47.
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