"Commander Kinsey" wrote in message
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On Thu, 03 Oct 2019 19:29:42 +0100, Robert wrote:

On 03/10/2019 14:29, Commander Kinsey wrote:
Why do LEDs generate heat? I want a technical answer not "because
they're inefficient". And will we ever make them more efficient?
Besides the inefficiencies in the LED itself which other posters have
covered, LED lamps have some current regulation or power supply built-in
which will not be 100% efficient and thus generates heat.

True, but it's the LEDs themselves that are the warmest, and also the most
susceptible to heat.

But if you feel a Philips Hue bulb which is the size of an old tungsten 100W
bulb, the part that gives off light (presumably where the LEDs are) is cool.
It is the neck, near the fitting, which gets hot - and I presume that's
where the PSU is.

Likewise for GU10 bulbs (Philips Hue or ordinary non-dimmable LED) the front
and conical sides don't get hot, whereas the neck near the fitting gets hot.