All of the electricity turns to heat in any case. The problem is the nature of incandescence. Incandescent filaments are black-body radiators. The spectrum o

All of the electricity turns to heat in any case. The problem is the nature of incandescence. Incandescent filaments are black-body radiators. The spectrum of black body radiation changes with temperature[1], so filaments that run hotter emit a larger proportion of their energy in the visible spectrum. [1] https://upload.wikimedia.org/wikipedia/commons/1/19/Black_body.svg https://upload.wikimedia.org/wikipedia/commons/1/19/Black_bo...