What is the significance of phase inversion in an operational amplifier?

[Hyperspace2]

In inverting operational amplifier when the signal is sent in -(minus) side then the signal is inverted at output. what does that mean? Whether it starts from postive half cycle or negative half cycle , it is an ac. I don't think it will make physical differences. I am so confused. Anyone can help. Advance thanks.

 

[granpa]

http://en.wikipedia.org/wiki/Operational_amplifier_applications#Differential_amplifier

 

[nivaOne]

Consider it a pulley.
If you pull the rope downwards then the other side goes upwards. And vice versa.

So it means when the input voltage rises, the output voltage will lower.

 

[Hyperspace2]

Consider it a pulley.
If you pull the rope downwards then the other side goes upwards. And vice versa.

So it means when the input voltage rises, the output voltage will lower.

I wasn't talking about that . I was talking about following phrases


"A signal fed into the + input (non-inverting) will produce an output signal that is in phase with the input signal. A signal fed into the - input (inverting) will produce an output signal that is 180 degrees out of phase with the input signal"

I was just trying to ask what is the differences between the input signal and the output signal that is 180 degrees out of phase of the input signal. I see them same ,because anyway they are the ac signal .

 

[nivaOne]

I wasn't talking about that . I was talking about following phrases


"A signal fed into the + input (non-inverting) will produce an output signal that is in phase with the input signal. A signal fed into the - input (inverting) will produce an output signal that is 180 degrees out of phase with the input signal"

I was just trying to ask what is the differences between the input signal and the output signal that is 180 degrees out of phase of the input signal. I see them same ,because anyway they are the ac signal .

Hi,
If you look at each signal individually, you would only see signals with the same shape and frequency.
But if you would use an oscilloscope, you would see the difference.

 

[sophiecentaur]

If you look at your signals with a single channel oscilloscope then you will not see any 'inversion' - the scope will trigger the same way whatever phase of signal you give it and your "arc signal" will look the same, (or perhaps a different amplitude). You will only be aware of a phase difference if you show input signal (to trigger the scope with) on one channel and look at the two output signals, in turn, on the other channel. One will be in phase with the input and the other will be the other way up - in antiphase.