Practical integrator op amp

Purpose: in this experiment, we connect op amp with the first order circuit, and draw the graph with different waveforms.

Sketch the input and output waveforms fro 1kHz sin wave, trangle wave, and square wave input.

sine wave

square wave

trangle wave

Question
Note that 10MΩ resistor is not in the ideal integrator circuit. what is there for? (think about what would happen if a small DC component in the input waveform. waht would integrating this constant do after a short time?) what happens when it is removed?
A: If we remove the 10MΩ resistor, the Rf will become the value of capacitor. In the become of charge capacitor, the resistance of its is infinite, so the gain A will become infinite/Rin= infinite and get error. Inserting a 10MΩ resistor will make the gain =infinite*10M/(infinite+10M)= 10M, and it is an acceptance gain.