op-amp doubt

[krishnenduk]

can anyone explain me in layman terms how an op-amp follows its input in a voltage follower? My doubt is, as the output is same as the input, in the next cycle both the inputs will be same voltage and as a basic operation voltage at the inverting terminal gets subtracted from non-inverting terminal and as a resull output must be 0.. But we are getting the same output as input.. how??

 

[Resqueline]

I'm not able to follow your reasoning, but think of it like this:
The op-amp actually just amplifies the voltage-differential between its inputs by something like 100000 times. So if the +in is 0.1mV higher than the -in then the output will be at +10V, and if the +in is 0.1mV lower than the -in then the output will be at -10V.
Connecting the output to the -in makes it follow the +in, for all practical purposes that is, you'll only lose 1/10th of a mV in full-swing amplitude.
This small voltage is usually measurable with a normally sensitive DVM, just take into consideration that there also may be an input-offset-voltage of several mV.