. A thermocouple is placed on one side of a solid 2 cm-thick 1 m x 1m (square) slab of aluminum, held at a uniform temperature of 25 o C. The surroundings are also at 25 degree celsius on both sides of the slab. At time t > 0, the side opposite the thermocouple is held at surface temperature of 100 degree celsius. Assuming heat flux only in the thickness direction (normal to the square side): a) Approximately how long will it be before the thermocouple begins reading a temperature different from 25 degree celsius? b) If the temperature on the hot side is held at 50 degree celsius, how does your answer change, and what considerations regarding the thermocouple performance must be made in answering this question? c) If the slab is made of concrete, under the conditions of part a), what is the estimated time for response of the thermocouple?