A so-called "buried" Zener voltage reference is special diode built onto a silicon chip so that it is co- located with a tiny little on-chip resistor used to maintain the Zener diode's junction at constant temperature 34.3C, just above room temperature (26C). The heater is turned on and off by a micropower electrical thermostat built elsewhere in the same silicon chip. That thermostat is designed to deliver a maximum of 895 milliWatts of heat to the Zener junction area of the chip, as needed. The whole chip is cemented between two ceramic covers of thickness 3.96mm and having a thermal conductivity of 6.64 W/mC. The whole chip is 4.35mm by 6.35mm and 3.35mm thick in size. To keep the reference voltage within spec (which is 10 ppm), the temperature of the junction cannot vary by more than 156.32 millikelvin. (a) Compute the time-average power load of the heater when the chip is at room temperature (b) What is the coldest temperature the enclosure of the chip be at and still deliver voltage within spec? mW Answer part (a) C Answer part (b)