A differential amplifier whose two input signals are equal, but 180 degrees out of phase, will have a ___________ output signal.

In a differential amplifier, the output is based on the difference between the two input signals. When the inputs are equal in magnitude but opposite in phase (180 degrees out of phase), they effectively cancel each other out. This results in the output being the algebraic difference between the two inputs, which is zero.

Consequently, because the differential amplifier is designed to amplify the difference, when the two signals are equal and opposite, the output signal reflects this cancellation, resulting in no output. Therefore, the output signal does not reach a maximum or a minimum because it is actually zero, indicating that a significant change is happening at the input level, which leads to no output change at the output level.

This means the correct outcome is that the output signal will be zero, which aligns with the concept that when identical signals are out of phase by 180 degrees, there is complete cancellation. Thus, the correct understanding directly correlates to the principles of how a differential amplifier operates regarding phase differences between two input signals.