When adding energy to generate EMR (in a light bulb, heat lamp, etc), what determines how much of the energy makes the light “bluer” (higher frequency per photon) and how much makes it “brighter” (more photons)?
When adding energy to generate EMR (in a light bulb, heat lamp, etc), what determines how much of the energy makes the light “bluer” (higher frequency per photon) and how much makes it “brighter” (more photons)?
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This just from my knowledge studying welding, but with light genetated by electricity (such as an electric arc) the wavelength of a photon is proportional to the voltage applied. More voltage = blue-er photons. We currently don’t have a power source or suitable lasing medium to hit gamma-ray level. “Brightness,” or the amount of photons, is proportional to amperage, which is why 110-amp welding arcs will burn you: an absolutely fuckoff large amount of photons streaming out.
Do you like quantum physics? This is how we get quantum physics. The short answer is the photon emission band. Different materials support different energy levels and if you can push the electrons to a particular level then the material will spit out a photon. This energy level will dictate what wavelength of photon is emitted.
There is a concept called quantum confinement where you can restrict electrons in multiple dimensions. This is super useful for selecting the wavelength of light. Quantum cascade lasers is on method and quantum dots is another. Quantum dots are made with a precise diameter and trap electrons at a specific energy level and allow for a very precise control of wavelength.
For more info, look up how blue light leds were invented. It was a multi year effort that I think lead to the development of III/V semiconductor technology.
In an incandescent light bulb, the distribution of photons is well-modeled by black-body radiation (https://en.m.wikipedia.org/wiki/Black-body_radiation). As you increase the power, the temperature of the filament increases, which shifts the peak frequency higher (the light is “bluer”) and also increases the number of photons of every frequency emitted (the light is “brighter”), in the specific way detailed by the black-body curve.
Other types of light bulbs, like fluorescent and LED bulbs, don’t generate light by heating up a filament, so their radiated spectrum is very different. In particular, they aren’t guaranteed to get “bluer” at higher power (and will probably break if you try).
Light bulbs and heat lamps emit thermal, or blackbody radiation. They emit light at a broad range of frequencies that depends on temperature. In the same lamp, adding energy increases the temperature of the filament, which not only changes the brightness but also the colour of the light.
In LEDs, the photon frequency is determined by the semiconductor materials used. Light is emitted when electrons jump across the “forbidden” energy gap, and thus the photons have frequency matching the size of this gap. Putting in more energy just changes brightness. Because the colour depends on the material, blue LEDs were such a big deal. Red and green LEDs are old technology, but blue LEDs enabled modern energy-efficient lighting technologies, which is why they were worth a Nobel prize.
It all depends on the method you use to create radiation.
See planck distributions – Black body radiation.
There will always be some photons of both red (read: low frequency) and violet (read: high frequency); more importantly there will be a continuous distribution of photons from the blue to the red parts of the spectrum. With Planck’s law, we can see that the intensity (read: brightness) peak, moves across the visible light range as temperature increases (all the way from ~700 kelvin and up), and we can simply accept the peak to be nearly the color we see.
But this is the distribution of intensity, brightness or even -> Flux (being the amount of flow per unit time through an area) of photons, and the frequency or wavelength, whichever you prefer.