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The Stefan-Boltzmann law for radiation gives the emissive power of a real surface as:
A{'text': '$E = \\sigma T$', 'label': 'A'}
B{'text': '$E = \\varepsilon\\sigma T_s^4$ — where ε is emissivity (0 ≤ ε ≤ 1) and σ is the Stefan-Boltzmann constant', 'label': 'B'}
C{'text': '$E = kAT$', 'label': 'C'}
D{'text': '$E = h(T_s - T_\\infty)$', 'label': 'D'}
Answer & Solution
Correct answer: B. {'text': '$E = \\varepsilon\\sigma T_s^4$ — where ε is emissivity (0 ≤ ε ≤ 1) and σ is the Stefan-Boltzmann constant', 'label': 'B'}
Stefan-Boltzmann: E = εσT_s⁴ (W/m²), with σ = 5.67×10⁻⁸ W/m²K⁴ and emissivity ε measuring deviation from a blackbody (ε=1). Note the FOURTH-power dependence on temperature.
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