Question

Noninverting Amplifier, the op-amp parameters are given as follows:
A = 200,000, Zin = 1MΩ and Zout=100Ω.
Calculate the amplifier input impedance (with negative feedback).

rf =47kΩ
ri = 1.0kΩ

a) 1kΩ
b) 2 MΩ
c)4.26 GΩ
d) 100GΩ