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strangr_legnd_martyr t1_j7lzy1d wrote

Reply to comment by Thelgow in TIL the first Blue LED wasn't commercially available until 1989 and bright blue LEDs weren't available until 1993. by j-merc23

Red LEDs do require less power. The forward voltage on a red LED is about 1.8V at 20mA. The forward voltage on a blue LED is about 3.6V. That's 36mW of power for red vs 72mW of power for blue.

Blue light has more energy than red light (higher frequency/shorter wavelength).

I think they generally favor red over blue for emergency systems, though, because red light has less effect on low-light vision. So if the power goes out, your red-lit emergency signs don't blind you in the dark.

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Thelgow t1_j7m0bd7 wrote

That too because lord knows what happens when the tape falls off my optical to rca adapter. Why this thing has a Batman spotlight built into it, I'll never know.

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Ok-disaster2022 t1_j7mdka0 wrote

However there's an issue with emergency signage. Red is the color of danger, stop, while green is safe, go. Exit signs in areas of low literacy are green and green are becoming more common in the US to be more inclusive of people who can't read.

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Marzgog t1_j7qj8dt wrote

My country has among the highest rates of literacy in the world and our exit signs are green. I don’t think inclusivity has anything to do with exit signs going green, it’s just one of those universal standards in the making.

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