i read in a book of Paul albert Malvino that when the load resistance of an opamp(in the book a 741C was used as example)decreases the maximum peak to peak output value also decreases. why is that?
it is the Electronic Principles 8th edition by the way and also why is it called maximum peak to peak? doesn't peak to peak already indicate the maximum?

 

Maximum peak to peak: If you use a smaller input you will get a smaller peak to peak output so there is an input level which will give you the maximum peak to peak output the circuit is capable of.

Why it changes with the load: Every source of voltage has some series resistance no matter whether it is the mains supply, an AAA battery, or the output of an opamp. When you connect a lower load resistance, which draws more current, some voltage is dropped across that series resistance and so the available voltage is reduced.

 

The output of the OpAmp is either bipolar or mosfet. Taking the
bipolar case, as the load is decreased the current demand
from the driving transistors goes up as the gain loop tries to adjust.
But the transistors have finite geometries, and when the
CB junction becomes forward biased the Ic will drop. Its more
complicated, an explanation here -

https://people.eecs.berkeley.edu/~hu/Chenming-Hu_ch8.pdf

Regards, Dana.

 

The output of the OpAmp is either bipolar or mosfet. Taking the
bipolar case, as the load is decreased the current demand
from the driving transistors goes up as the gain loop tries to adjust.
But the transistors have finite geometries, and when the
CB junction becomes forward biased the Ic will drop. Its more
complicated, an explanation here -

https://people.eecs.berkeley.edu/~hu/Chenming-Hu_ch8.pdf

Regards, Dana.

thank you Dana