On Fri, 04 Oct 2019 23:54:39 +0100, Dave W wrote:

On Thu, 3 Oct 2019 06:37:34 -0700 (PDT), whisky-dave
wrote:

On Thursday, 3 October 2019 14:29:30 UTC+1, Commander Kinsey wrote:
Why do LEDs generate heat? I want a technical answer not "because they're inefficient".

That is the technical answer just lioke why does a wire get hot when curremnt passes through it.

And will we ever make them more efficient?

Probably.

If you plot voltage across the LED versus current through it, the
curve is not linear like a resistor. At low voltage it hardly
conducts, but at higher voltage it conducts a lot, and the curve
flattens like a not very good zener diode, limiting the voltage.

It only limits it for a while, then you get smoke.

Voltage times current equals watts i.e. heat plus a little light.
Light has a power but it's miniscule. Complicated physics theory might
explain how the light is produced and why so little of it, but we
lesser mortals wouldn't be able to understand it.

I always thought an incandescent bulb was 1% light, 99% heat.
A fluorescent tube was 5% light, 95% heat.
And an LED was 10% light, 90% heat.

As a ratio those are about right. 100W tungsten = 20W fluorescent = 10W LED.

But I've been told elsewhere that LEDs are 40% efficient.