Heat Transfer - Radiation: Practice Problem & Solution
A blackbody and a real body of identical dimensions are heated to same temperature. If ratio of rates of radiation of the blackbody and the real body is \(4 : 3\), then emissivity of the real body is equal to
Solution Explained:
To solve this problem, we apply the core principles of Heat Transfer - Radiation. Understanding the underlying formula is key to arriving at the correct answer below:
The rate of radiation of a blackbody is \(E_b = \sigma A T^4\) and for a real body is \(E = e \sigma A T^4\). Given \(\frac{E_b}{E} = \frac{4}{3}\), we have \(\frac{1}{e} = \frac{4}{3}\), which gives emissivity \(e = \frac{3}{4} = 0.75\).
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