Advanced Qualification · A-002 Advanced components and circuits · A-002-008-005
What is the input impedance of a theoretically ideal op-amp?
- A Exactly 1000 ohms
- B Very high
- C Very low
- D Exactly 100 ohms
Correct answer: B — Very high. From the official ISED question bank, verified word for word.
Why
A theoretically ideal operational amplifier, or op-amp, is designed to sense voltage without drawing any current from the source, which means its input impedance must be extremely large. The full explanation — and one for every question — is in Pro.
Practise this section
Advanced components and circuits: semiconductors, amplifier classes, oscillators, mixers, filters and digital logic.