Which of these amplifiers provides a high input resistance and a variable gain?
A)open-loop amp
B)non-inverting amp with a rheostat as Rf.
C)inverting amp
D)voltage-follower amp

Question

Quizplus · Accepted Answer

The non-inverting amplifier with a rheostat as Rf provides a high input resistance (since the input impedance of the non-inverting amplifier is very high) and a variable gain (since the gain is determined by the ratio of the input resistor and feedback resistor, and the feedback resistor in this case is a rheostat that can be varied). The other options do not provide both a high input resistance and a variable gain.

Which of These Amplifiers Provides a High Input Resistance and a Variable