Define positive feedback

Positive feedback is a process that occurs in a feedback loop in which the effects of a small disturbance on a system include an increase in the magnitude of the perturbation. That is, A produces more of B which in turn produces more of A. In other words, it is the enhancement or amplification of an effect by its own influence on the process that gives rise to it.

For example, in the case of a public address system, the sound from the speaker can be picked up by the microphone to produce further sound through the speaker, leading to a loud squeal or whistle. This is an example of positive feedback.

Positive feedback is also seen in biological systems such as childbirth. During childbirth, the release of oxytocin causes contractions that lead to more intense contractions, releasing more oxytocin. This cycle continues until the baby is born.

In summary, positive feedback amplifies the effects of a system, leading to an exponential increase or decrease, rather than stabilizing the system.