Your answer is partially correct. Consider a power transistor encapsulated in an aluminum case that is attached at its base to a square aluminum plate of thermal conductivity k = 240 W/m-K, thickness L = 8 mm, and width W = 24 mm. The case is joined to the plate by screws that maintain a contact pressure of 1 bar, and the back surface of the plate transfers heat by natural convection and radiation to ambient air and large surroundings at T = Tsur = 30°C. The surface has an emissivity of ε = 0.9, and the convection coefficient is h = 48 W/m²-K. The case is completely enclosed such that heat transfer may be assumed to occur exclusively through the base plate. Ts.p = 9max 357.9 Transistor case Tsc. Pelec i 0.5992 Enclosure K 1 If the air-filled aluminum-to-aluminum interface is characterized by an area of A = 2 × 104 m² and a roughness of 10 µm and the surface temperature of the case, Tsc, is not to exceed 85°C, determine the maximum allowable power dissipation, in W, and the associated surface temperature of the power transistor, Ts.p. in K. W L ||| Tsur - Base plate, (k, e) -Interface, Ac -Ts.p Air Th

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Conduction and Convection

When energy travels from one object to another it is said to have undergone heat transfer. Heat transfer is nothing but the transfer of thermal energy or internal energy from one thing to another, like e.g., when a vessel with water, kept on top of a burner, heats up because of the flame underneath it.