How does a thermostat know how to keep hot soup hot and cold soup cold?

A thermos keeps thing hot or cold by using vacuum technology to keep air from getting inside. The double walled feature of the cup is what allows the container to be "vacuum sealed". In manufacturing the air between the two walls is removed creating the seal. The lack of air keeps the heat or cold from transfering, therefore letting it remain basically the same temperature.

answer; (arch); good luck

current and voltage can both be different in different parts of a circuit so it matters where you place the ammeter and voltmete