Question:medium
An iron furnace radiates \(42.5\) calories per second through an opening of cross-section \(1\ \text{cm}^2\). If the relative emittance of the furnace is \(0.80\), the temperature of furnace is given Stefan's constant \(\sigma=1.36\times10^{-8}\ \text{cal/m}^2\text{s K}^4\):
An iron furnace radiates \(42.5\) calories per second through an opening of cross-section \(1\ \text{cm}^2\). If the relative emittance of the furnace is \(0.80\), the temperature of furnace is given Stefan's constant \(\sigma=1.36\times10^{-8}\ \text{cal/m}^2\text{s K}^4\):
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For radiation problems, use \(P=e\sigma AT^4\) and convert area into SI units if \(\sigma\) is given in \(\text{m}^2\).
Updated On: May 19, 2026
- \(2500\ \text{K}\)
- \(273\ \text{K}\)
- \(373\ \text{K}\)
- \(500\ \text{K}\)
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The Correct Option is A
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