Heat Transfer - Radiation: Practice Problem & Solution

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 is given by $E = e\sigma A T^4$. For a blackbody, $e = 1$. Given $\frac{E_b}{E} = \frac{4}{3} ⇒ \frac{1}{e} = \frac{4}{3}$, hence emissivity $e = 0.75$.