Answer to Question #33618 in Electricity and Magnetism for rosan

Question

is all the electric energy coverted in to light in a bulb?

Answer 1

No, the main part of electric energy is converted into heat. Incandescent bulbs are much less efficient than most other types of lighting; most incandescent bulbs convert less than 5% of the energy they use into visible light (with the remaining energy being converted into heat). The luminous efficacy of a typical incandescent bulb is 16 lumens per watt, compared to the 60 lm/W of a compact fluorescent bulb. Some applications of the incandescent bulb deliberately use the heat generated by the filament. Such applications include incubators, brooding boxes for poultry, heat lights for reptile tanks, infrared heating for industrial heating and drying processes, lava lamps, and the Easy-Bake Oven toy.