bulb replacement, tail light 08?

That's what I said. Incandescents make white light which is then filtered.

Only white or close to white light is measured by color temperature. It's the temperature of a black body radiator that would emit light of that hue, so it only works for hues emitted that way. There is no green for instance. Non-white LED are usually measured by the wavelength of the light they emit, like 627 nm for a red LED.

 

Black body radiation is a characteristic curve, with a peak. That peak uniquely describes any example of black body radiation (and it temperature). This is how they know what temperature the microwave background radiation is.


So, there *is* a green. That is just black body radiation at a frequency in the range that we call green. It appears to US that it is white because, in order to have a peak in green, there needs to be a lot of red and blue, and our eyes short cut that into 'white'. Unlike green, there is no frequency of white light. White light just means a relatively spread spectrum. You can make white light with three lasers (pure light at only one frequency) for example.

Since LED are closer to lasers than to Black body radiators, it is therefore important to use an LED which is close to the color (frequency) that you want. Using a white LED that is made from three LEDs, RGB (not that they all are), would mean producing Red, Green, Blue only to filter out the Green and Blue. And actually it is worse than that, as most 'white' LEDs are blue with a bit of phosphor to spread the spectrum just enough to register as white to our eyes. Very little red at all in the mix.

 

*Some* incandescents make white light. Others make yellow, or even red light, that just isn't very popular. Halogens start to get up into the blue range. All those different colors are discernible to an objective instrument (a digital camera with auto white balance turned off). Our eyes have a really good white balancing system, and thus we see white paper regardless of the color of the light, pretty much.

 

Thanks to this thread, I was able to replace my light bulbs. Took me 15 seconds per side, thanks to the video. Pair of bulbs cost $5 at my local parts store. Sylvania 2235 is exact fit. I have a 2005 Prius.