CAPE Physics Unit 1 · 2016 · Paper 1 · Question Q36

The circular opening of a furnace has a radius of 6 \times 10^{-2}\text{ m} at 1450\text{ K}. It emits radiation equivalent to 60\% of that for a perfect black body radiator at the same temperature. What is the power radiated from the opening of the furnace?

1. (A)683\text{ W}
2. (B)1138\text{ W}
3. (C)1708\text{ W}
4. (D)2847\text{ W}