Inverting Operational amplifier

[Amith2006]

Homework Statement

1) Consider an inverting operational amplifier as shown in figure. Suppose R1= 1000 ohm & Rf = 10^6 ohm. It is said that the input impedance=R1=1000 ohm and the Output impedance= 0.

2) Consider a non inverting operational amplifier as shown in figure. Suppose R1= 3500 ohm & Rf = 15000 ohm. It is said that the input impedance=infinite. Why is it so? Here Rf is the feedback resistor.But only for an ideal Op-Amp, the input impedance is infinite and not for a real one, isn’t it? So, can R1 be taken as the input impedance of the Op-Amp in both cases?

Homework Equations

The Attempt at a Solution

 

[ranger]

These are a couple of links that explain the input impedance for both op amps.
http://www.phys.uAlberta.ca/~gingrich/phys395/notes/node102.html
http://www.phys.uAlberta.ca/~gingrich/phys395/notes/node103.html

For a real non inverting op amp, the input impedance is somewhere between 1 MΩ to 10 TΩ.