4-103 In a vacuum chamber, a thick slab is placed under an array of laser diodes with an output constant pulse. A thermocouple is inserted inside the slab at 25mm from the surface, and the slab has an initial uniform temperature of 20C. The known properties of the slab are k=63.9W/mK and a=18.8106m2/s. If the thermocouple measured a temperature of 130C after the slab surface has been exposed to the laser pulse, for 30s, determine (a) the amount of energy per unit surface area directed on the slab surface and (b) the thermocouple reading after 60s has elapsed. FIGURE P4-103