4 ms·
Is this (fluorescent materials) why the lights on laptop power cables now slowly fade out when unplugged, as opposed to suddenly turning off? Just a small quest
by aimor 6y ago
Is this (fluorescent materials) why the lights on laptop power cables now slowly fade out when unplugged, as opposed to suddenly turning off? Just a small question that's been in the back of my mind for awhile.
- icegreentea2 6y agoProbably not. Fluorescence occurs on a nanosecond timescale. Phosphorescence (what's used to make white LEDs) can have timescales on the order of seconds. What's far more likely is that it's a capacitor discharging.
- aimor 6y agoThanks for the answer and explaining the difference between the two.
- scottlawson 6y agoThe slow fade is because there is a large electrolytic capacitor in the power supply which retains a small amount of energy when the power supply is unplugged. This slowly drains (depending on circuit) and is why it sometimes take up to a minute to see the LED fade. When repairing or modifying power supplies it is important to be aware that capacitors may still be storing enough energy to cause a shock.