Op amp output voltage with V+ at 2.5V and V- not connected

[mohamad hajj]

suppose an amplifier with V+ is 2.5 volts
and V- is not connected...V- and Voutput are connected by a resistor.
what is the voltage on the outpout of the op amp?

 

[Bob S]

This is a non-inverting op-amp configuration with a gain of one, sometimes called a voltage follower.

Bob S

 

[yungman]

+2.5v.

 

[mohamad hajj]

the V- is not connected. (even not connected to ground reference)
the voltage at V- is zero or +2.5 volts like V+ or what?
thank you

 

[Bob S]

Is V- connected to Voutput through a resistor R, and not connected to anything else? What do you think the voltage drop in the resistor R is? Where does the resistor current come from? Have you ever heard about input bias current? Look at section 2.3 in

http://en.wikipedia.org/wiki/Operational_amplifier_applications#Non-inverting_amplifier

and set R₁ to ∞.

Bob S