What will happen if a signal is applied to the input of the amplifier from its output?

Question

Physics

Google did not help on this issue (perhaps I incorrectly formulated the search query).

Answer 1

Positive feedback and self-excitation. Possible consequences - failure or operation of protection. Functionality will be broken in any case.

Answer 2

"microphone effect"

Answer 3

It is not difficult to understand that it will burn out almost immediately.

Answer 4

Get feedback. And what will happen depends on the "ideality" of the amplifier and the specifics. It might burn out.