If there was no feedback in an oven system, it would keep getting hotter until it melted, exploded, or was turned off.
The particles of the gas will heat up, move faster and collide with each other more, increasing the pressure and the can will explode.
The light inside would turn on, the turntable would spin, the timer would count down, and this would all continue until the timer reached zero, at which time everything would shut off. Most manuals advise against doing this, because if there's nothing in the oven to absorb the microwaves they can reflect back and damage the klystron (the part that actually generates the microwaves).
Microwave oven
toaster oven
Oven shelves contract while cold. When heat is introduced, they expand (or grow larger) and can damage your oven walls.
it melts
The system without feedback is known as open loop system. The examples of the open loop system are bread toaster, oven ,washing machine. The open loop systems are inaccurate & less complex.
Putting metal in the microwave can cause a fire to happen.
The roast I just put in the oven would be ruined in about an hour.
You will have a slightly higher utility bill
oven thermostatheating/air conditioning thermostatcruise controlautomatic gain control in a radio/TV receiverthe system in a steel rolling mill to keep the rolled sheet of metal constant thicknessetc.
The negative feedback mechanism is important in many biological processes. The process can be shut off by the accumulation of products further along in the process.
It will melt
not usually, but it does happen
Cardboard one would just blacken on the edges. Styrofoam would melt and probably catch fire.
nothing
It will shrivel up and burn