# phy

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Calculate the electric power which must be supplied to the filament of of a light bulb operating at 3000K. The total surface area of the filament is
8×10−6m2
and its emissivity is 0.92.

• phy -

R=kσT⁴ = 0.92•5.67•10⁻⁸•3000⁴=… W/m²
R=P/A =>
P=AR= A•kσT⁴ =
=8•10⁻⁶•0.92•5.67•10⁻⁸•3000⁴= 33.8 W

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