What is an example of positive feedback?

An example of a positive feedback loop is found in the light switch.

A positive feedback loop is a circuit that amplifies the signal applied to the circuit. In the classic form it consists of a loop of amplifiers and resistors, with the loop connecting each amplifier to a current source. For example:

The light bulb on the left is a load to the current source on the right. The current source generates a current that rises as the input to the current source rises. When the current source has produced enough current the voltage across the bulb rises, which raises the current. The current rises, and the process repeats, giving rise to a constant output voltage.

Another example of a positive feedback loop might be as follows: The lamp's filament is the load on the current source. The current rises when the filament turns on, and the current keeps rising as long as the filament is on.

Here the transistor acts like the current source. As the input voltage rises, the collector current rises, causing the emitter voltage to rise. This in turn increases the input voltage, which further increases the collector current.

A simple example of a positive feedback loop can be found in the earphone. The loop consists of the speaker, the wire from the headphone jack on the cord to the speaker, the wire from the speaker to the speaker's amplifier circuit (the actual amplifier is not necessary - just anything connected to the amplifier and wired in the loop will work). The current that is fed to the speaker's amplifier circuit causes a voltage increase to occur at the speaker. This voltage increase then causes another voltage increase at the speaker - it is an example of positive feedback.

There are three basic examples of positive feedback circuits, namely. 1) The negative feedback circuit as used in audio amplifiers (and other amplifiers where the negative feedback reduces the output). 2) Feedback loops in electrical circuits where one component supplies the power for the component in the feedback loop. The loop is positive feedback when the energy from the source is fed back to the source.

3) Positive feedback loops in electronic circuits, as mentioned by @D.E.S.

What are some examples of positive feedback for peers?

For your specific question about peer feedback, we need to get more into what you are asking about here. You seem to be asking about peer feedback, but this may not be the same thing as peer feedback. The word peer is used in two senses in the English language, and the distinction between them may not be obvious. The following are good definitions for those two senses of peer:

1 A person (usually a member of a group) with whom one shares or exchanges ideas, attitudes, etc.: "a colleague in his department" (Oxford English Dictionary).2 The person, usually a man, who is one's equal, especially intelligence and ability: "this new peer at the office" (Random House).

There is a third sense of peer, and this sense is also the sense that you may have intended. This third sense of peer can be used to mean a person who is like a peer in some way, but the adjective is being used in the ordinary sense of "equal", "opposite" or "antagonistic". For example, in the sentence "I like the way that my peer is working", the first definition of peer is being used. It is not used in a way that would be relevant to the question you asked. The second definition is being used in the sentence.

The difference between the third sense of peer and the second sense is that the third sense requires a comparison to someone who is equal to the speaker. In this case, it is used to mean someone who is equivalent to the speaker intelligence or ability. For example,

4 An antagonist (as in a theatrical play): "he was my adversary, but he was no peer of mine" (Oxford English Dictionary). In the sentence, your second definition of peer would be the third sense of peer in the sentence "I like the way that my peer is working", and your first definition would be the second sense of peer in the sentence. Since the distinction between the first and second sense of peer is not always clear, your question may have been ambiguous.