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Physics - Heat & Thermo Question with Solution | TestHub

PhysicsHeat & ThermoHeat TransferMedium2 min

PhysicsMediuminteger

A lamp filament of length 0.20 m and diameter 0.05 mm is rated at 60 W. It radiates 70% as much as a black body at the same temperature. Take $σ = 5.67 \times 1 0^{- 8}$ W m⁻² K⁻⁴ and find its temperature, in K.

Answer:

2634

Solution:

$A = π d l = 3.142 \times 1 0^{- 5}$ m². $T^{4} = \frac{60}{0.7 \times 5.67 \times 1 0 ^{- 8} \times 3.142 \times 1 0 ^{- 5}} = 4.812 \times 1 0^{13}$ , so $T = 2634$ K.

Subject:PhysicsTopic:Heat & ThermoSubtopic:Heat Transfer

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