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A thin brass rectangular sheet of sides 15.0 and 12.0 cm is heated in a furnace to `600^@` C and taken out. How much electric power is needed to maintain the sheet at this temperature, given that its emissivity is 0.250?
Neglect heat loss due to convection (Stefan-Boltzmann constant, `sigma=5.67xx10^-8 W//m^(2)-K^(4)`).

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