For what portion of a cycle does a Class B amplifier operate?

A Class B amplifier is biased exactly at the cutoff point. This means the active amplifying device only conducts current during exactly half of the input signal's sine wave, which corresponds to 180 degrees of the 360-degree cycle. Because a single Class B amplifier only reproduces half of the waveform, it creates severe distortion on its own. To reconstruct the full wave, two Class B devices are typically used together in a 'push-pull' arrangement, where one handles the positive 180 degrees and the other handles the negative 180 degrees. Selecting 'the entire cycle' would incorrectly describe a Class A amplifier, while 'less than 180 degrees' describes a Class C amplifier.