1.what is the main cause for the emf produced in a thermocouple when their two junctions are at different temperatures? 2.why is it necessary that the emf produced causes the current to pass from the metal (which is at the top of thermoelectric series) to the other metal (which is at lower position) at the cold junction?? for eg:if we use a thermocouple of iron and copper and two junctions are at temperatures (lets say) 100 and 0 degree celcius...then it is said that the current flows from iron(which has higher position in thermoelectric series) to copper (which has lower position in thermoelectric series) at cold junction(0 degre celcius)..but why can't the current pas from iron to copper in the hot junction itself??? isn't it the same? 3. At inversion temperature the flow of current is reversed ...why does this happen??