1. A thermometer having an emissivity of 0.9 is placed in a large room and indicates a temperature of 25?C.The walls of the room are at 35?C and the convection heat transfer coefficient is 5.0 W/m2 · ?C. Calculate the true temperature of the air.
2. A stainless-steel sphere having a diameter of 3.0 mm is embedded with a copper constantan thermocouple and is suddenly exposed to air at 50?C with a convection coefficient of 20 W/m2 · ?C. The initial temperature of the sphere is 20?C. Plot the output of the thermocouple as a function of time. What is the time constant?