# Op amp question

1. Mar 13, 2014

### rzn972

1. The problem statement, all variables and given/known data

What is the output voltage for an op amp whose non-inverting input is connected to ground and its inverting-input voltage is 4mv? Assume that the op-amp open-loop gain is 2*10^5 and its supply voltage is Vcc=10V

2. Relevant equations
Vo= A(vp-vn)

3. The attempt at a solution
The problem gives
Vn= 4mv
A=2*10^5
Vcc=10V
Since it says the non-inverting input is connected to ground, does that mean vp=0?
Vo=2*10^5(0-.004V)
Vo=-800 V
However the answer is suppose to be -10V. What am I doing wrong?
Thanks for helping!

2. Mar 13, 2014

### Staff: Mentor

Can the output of an op-amp ever exceed its power supply voltages (positive and negative supplies)?

3. Mar 13, 2014

### rzn972

Ahh, I see so the max Vo is 10 and min Vo is -10. So is what I did wrong? Do I have the write down that calulated vo= -800 but say the min is -10V.

4. Mar 13, 2014

### Staff: Mentor

That's the idea. Do the calculation and then state why in actuality the value will be "truncated" by the limits imposed by the power source.

5. Mar 13, 2014

### rzn972

Thank you so much!