Solving for Output Voltage of Op Amp

[rzn972]

Homework Statement

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

Homework Equations

Vo= A(vp-vn)

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!

 

[gneill]

Homework Statement

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

Homework Equations

Vo= A(vp-vn)

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!

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

 

[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.

 

[gneill]

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.

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.

 

[rzn972]

Thank you so much!