Incandescent lightbulbs produce light when electrons (electric current) move through the filament and collide with tungsten atoms and ions in the filament, causing them to vibrate violently. accelerating charged particles emit electromagnetic radiation. this is true for vibrating and accelerating particles in the filament, in your skin, and on the sun. the 35 ∘c skin of a person emits most of its radiation in the low-frequency, long-wavelength infrared−sometimes called thermal radiation. at 2500 ∘c, the filament of an incandescent lightbulb emits most of its radiation as higher frequency infrared radiation and just 10% as visible light (very inefficient if the goal is to produce light). at 6000 ∘c, the sun emits about 45% in the infrared range and 40% in the visible light range.
banning incandescent bulbs will reduce energy usage. according to the department of energy, about 1018j of electric energy is used each year in the united states for household lighting. compact fluorescent lightbulbs (cfls) and light-emitting diode (led) bulbs use about one-fourth the energy of incandescent bulbs. switching to cfls and leds would also reduce greenhouse gas emissions by reducing the need for power produced by coal-burning electric power plants.
suppose you changed all incandescent lightbulbs to more energy-efficient bulbs that used one-fourth the amount of energy to produce the same light. about how many 3.1×109-kw⋅h/year electric power plants could be removed from the power grid? remember that answer should be rounded up.