25.7 Exercise 27

Referring to the electric room heater considered in the first example in this section, calculate the intensity of IR radiation in $\text{W}/\text{m}^{2}$ projected by the concave mirror on a person 3.00 m away. Assume that the heating element radiates 1500 W and has an area of $\text{100} \text{ cm}^{2}$, and that half of the radiated power is reflected and focused by the mirror.