On Tue, 25 Apr 2017 13:27:49 +0100, Graham. wrote:

On Tue, 25 Apr 2017 12:25:35 +0100, "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. I would have expected it to have a white coating that can be seen like on a switched off fluorescent tube.

--
When you want a man to play with you, wear a full-length black nightgown with buttons all over it.
Sure it's uncomfortable, but it makes you look just like his remote control.