A voltage follower is an operational amplifier connected so that its gain is:
Anegative, to invert the phase of the signal
Bvery high, to amplify weak input signals
Cunity, giving a high input and low output impedance
Dzero, to block the signal completely
Answer & Solution
Correct answer: C. unity, giving a high input and low output impedance
1. A voltage follower feeds the entire output back to the inverting input.
2. Putting $R_f=0$ into $A=1+\dfrac{R_f}{R_1}$ gives a gain of 1, so the output follows the input exactly.
3. Its value is not amplification but impedance: it presents a very high input impedance and a very low output impedance.
4. That lets it take a signal from a weak source without loading it down, and drive a demanding load.
5. This use as a buffer between two stages is the importance the configuration is known for.
_Source: NECTA ACSEE 2023 Physics 131/1, Question 9: Electronics (Semiconductors,Logic Gates & Op-Amps)_