A black thermocouple is used to measure the internal temperature of a furnace having black walls. If the air around the thermocouple is at 20degreeC and the walls are at 100degreeC, what temperature will the thermocouple read? [The heat transfer coefficient between the thermocouple and air is 75 W/m2K]. Comment what will happen if the walls are not black and we use a white thermocouple.