The intensity of solar radiation is maximum at a wavelength of 0.49 μm. Assuming the Sun as a black body, what is the approximate total emissive power of the Sun? [Consider Wien's displacement constant = 2890 μm-K]

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Answer 1

Concept:

Using Stefan–Boltzmann Law for a black body:

$ E = \sigma T^4 $

To find temperature, apply Wien's Law:

$ \lambda_{\text{max}} T = b \Rightarrow T = \frac{2890}{0.49} = 5897.96~K $

Now calculate:

$ E = 5.67 \times 10^{-8} \cdot (5897.96)^4 \approx 6.86 \times 10^7~\text{W/m}^2 = 6.86 \times 10^4~\text{kW/m}^2 $