I have this problem and it's something that's been annoying me all day that I just can't get my head around. Imagine a metal block, in direct thermal contact with a heating element and "the surroundings"; but the heater and "the surroundings" are not in direct thermal contact. (I'm supposing also that the surroundings will remain at a constant temperature). The heater is turned on with a constant potential difference and constant current running through it. The effect is to heat the block. My question is: will the block reach the same temperature as the heating element, or will it reach a steady temperature somewhere in between the temperature of the surroundings and the heating element, due to constant heating of "the surroundings" by the metal block? Or alternately, would this depend on the conditions of the system, like the heat capacity of the metal block and its surface area? I will happily accept a condescending response because I think I may just be over-thinking this problem and missing a blindingly obvious answer!