Ex: Police Lightbars, they’re so bright but use so little of the cars battery. Much less than the classic rotating lights.
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Incandescent lights work by black body radiation. Essentially, they get a piece of metal hot. Some heat gets radiated as energy. The hotter (and more energetic) the object, the more energy it radiates, and the more of that energy gets radiated at higher frequencies. So if you pump enough electrons into a piece of metal, it’ll get hot enough to glow in the visible light spectrum. But you’re wasting a bunch of energy by radiating in the infrared spectrum as well.
LEDs emit light in a much more straightforward manner. Basically, when electrons need to lose energy, they jettison it in the form of a photon. LED materials have “electron holes” of a certain “depth” so that electrons that “fall down” the hole emit energy in the desired wavelength. You’re basically directly converting electricity into the wavelength of light you want, instead of heating up metal to get light as a side effect.
Light gets emitted by electrons when they drop energy levels, emitting a packet of energy.
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