An array of power transistors, dissipating 6 W of power each, are to be cooled by mounting them on a 25-cm × 25-cm-square aluminum plate and blowing air at 35°C over the plate with a fan at a velocity of 4 m/s. The average temperature of the plate is not to exceed 65°C. Assuming the heat transfer from the back side of the plate to be negligible and disregarding radiation, determine the number of transistors that can be placed on this plate.

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Aluminum Power plate transistor, 6 W 35°C 25 cm Air 4 m/s 65°C 25 cm