Question

The input resistance of op-amp is
A. very high
B. very low
C. zero
D. one

Answer 1

Hint An Operational Amplifier is a fundamentally a Voltage amplifying device. When the potential is amplified the resistance is very high. The resistance is high so that the current flowing in the circuit is little and thereby protects loading in the circuit.

Complete Step by step solution
An Operational Amplifier also known as op-amp is a high gain electronic voltage amplifying device with a differential input and single ended output. It is designed to be used with external feedback components such as resistors and capacitors. The output potential obtained is usually 100,000 times larger than the input potential.
As the Potential is being amplified, the input resistance for an ideal Op-Amp is infinite or very high. This ensures that op-amp utilises every little current in the circuit and this protects loading issues in the circuit.
The output resistance for an ideal Op-amp is zero because in that way the output voltage remains unaffected even if the external load draws out any current.

Hence the answer is Very High that is option (A)

Note: input Resistance in ideal cases for an Om-Amp is infinite so as to consume every little current from the circuit. And the output resistance is to be taken as 0 so that the output potential remains unaffected even if the external load draws out any current.