Ok I'm totally out of my depth here as I'm only a student but I'm confused about the relationship between the emissivity and black-body characteristics of tungsten. I'm not sure if my fundamental understanding of the topics is incorrect but here is my research:
Spectral emissivity is the ratio of energy radiated from a real material's surface compared with that radiated from a perfect black-body at the same temperature, wavelength and observing angle. The closer this ratio is to one, the closer the material is to a good black-body
Tungsten has a spectral emissivity that averages about 0.4 depending on temperature, age etc.
Tungsten filaments in incandescent lights are very good representations of black bodies.
But how can the spectral emissivity of tungsten be so low but an incandescent bulb be almost a perfect black-body?
Best Answer
If the emissivity does not strongly depend on frequency in the relevant range the emitted spectrum will be like that of a black body, just with lower intensity.