James Wilkinson Sword wrote
Graham. wrote
James Wilkinson Sword wrote

Yes, I've googled it, but there are many different approaches.
Which one is used in domestic LED bulbs?

Ultra-violet LED exciting a white phosphor,
much the same principle used in florescents.

That's what I would have assumed, but when you
look at a switched off white LED, it's not white.

All that means is that it isnt white when it doesn't have UV falling
on it and that the protective outer isnt the phosphor itself.

I would have expected it to have a white coating that
can be seen like on a switched off fluorescent tube.

The difference is that leds don't have glass as the protective outer.