Operational Amplifiers - Technical MCQs

Q1:

mcq18_1012.gifWhat value of input resistance is needed in the given circuit to produce the given output voltage?

A 50 omega.gif

B 4 komega.gif

C 4.08 komega.gif

D 5 komega.gif

ANS:B - 4 komega.gif

Rì =( rf/Vout) * Vin.
= (200k/ 3) * 60m. (Since k and m cut each other).
= (200/ 3)* 60,
= 200* 20,
= 4000,
= 4k.