this post was submitted on 01 Apr 2024
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Showerthoughts

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A "Showerthought" is a simple term used to describe the thoughts that pop into your head while you're doing everyday things like taking a shower, driving, or just daydreaming. A showerthought should offer a unique perspective on an ordinary part of life.

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Night lights that detect light levels are probably flickering so fast that it just appears to be on (lemmy.world)
submitted 7 months ago by rockSlayer@lemmy.world to c/showerthoughts@lemmy.world
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Ok so I got this idea not while showering, but because I'm very high. The story does come from my bathroom though! I have a night light in my bathroom, and I was looking at the night light as I turned off the bathroom light. I'm a big nerd so I remembered that the things that detect light levels are actually diodes wired in reverse. I thought it would be funny to make it flicker by reflecting the light back on the diode, but it didn't work. That's when I had this realization

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[–] MentalEdge@sopuli.xyz 5 points 7 months ago* (last edited 7 months ago) (1 children)

While that's true, in between the voltage spike in either direction there is a moment of equilibrium that is equivalent to "off".

This moment lasts for too short a time to matter, as the voltage goes up and down smoothly in the pattern of a sine wave, meaning the time spent in the true "off" state is infinitesimally small, not 1/60 of a second as the frequency would suggest.

But even then the filaments temperature does fluctuate with the flips in voltage. It again just doesn't matter, as it becomes sufficiently energised again before it even cools enough to stop glowing.

Cheap LEDs stop glowing much quicker than a filament, which is why they can flicker even when the AC is rectified into DC, if done without a capacitor to smooth out the voltage.