Longshadow wrote:
Incandescent lights are so slow to cool down and "turn off" compared to 60Hz that they never really go dark between cycles. I'd question if they even dim.
LEDs, being a semiconductor, are closer to instantaneous on and off. Look at the difference between LED and incandescent bulb brake lights. Incandescent "ramp up" and down while LEDs are "bam", on, bam, off.
When I was in school, I conducted an experiment. I was able to transmit speech using an incandescent bulb in a flashlight like reflector to a photocell. I was surprised how well it worked. That doesn't imply that the light went completely "off", but it certainly "dimmed".
Actually, LED's dim when the current is low. But they do "bam" off on cars' stop lights when the current stops unlike incandescent bulbs that dim down to off as they cool.