Chips of width l = 15 mm on a side are mounted to a substrate that is installed in an enclosure whose walls and air are maintained at a temperature of tsur =t=25c. the chips have an emissivity of 0.60 and amaximum allowable temperature of ts = 85 c. (a) if heat is rejected from the chips by radiation and natural convection, what is the maximum operating power of each chip? the convection coefficient depends on the chip-to-air temperature difference and may be approximated as h = c(ts – t) 1/4, where c = 4.2 w/m2 k 5/4 . (b) if a fan is used to maintain air flow through the enclosure and heat transfer is by forced convection, with h = 250 w/m2 k, what is the maximum operating power?