How does a thermostat in a refrigerator work?
It most probably uses a bimetallic strip to sense temperature, and closes a contact when the temperature goes above a set point. The closed contact turns on the compressor, which starts cooling the refrigerator. After a bit, the temperature goes low enough and the contact opens, turning off the compressor. This cycle continues. negative feedback, from the top of my head, is a process where an error signal is amplified and used to control a process that decreases the error. The error signal is the difference between the desired temperature and the actual temperature, which is sensed by the bimetallic strip and (amplified) used to control the compressor, which will decrease the error, ie, cool the frig. A bimetallic strip is a long thin strip consisting of two dissimilar metals soldered or riveted together, and wound into a coil. Since the two metals have different thermal expansion properties, as the temperature changes the coil winds tighter or unwinds. This causes to contacts to close
