Eli5 Why is it that, in some rooms, when you turn on the light there’s a delay, but when you switch it off, it turns off instantly?

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Eli5 Why is it that, in some rooms, when you turn on the light there’s a delay, but when you switch it off, it turns off instantly?

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Anonymous 0 Comments

When you see a brief delay in turning on a light, it’s because either the lamp has some kind of ballast or driving system that has to charge up, or because you’re using some kind of “smart” device to control the lights, and it takes a moment to detect the input and change the state of the lamps.

Incandescent bulbs will turn on instantly when power is applied. However, fluorescent and LED bulbs may take a moment to light up because they have control circuitry in them that must power up before power is delivered to the actual element that provides light, or in the case of fluorescent bulbs, the gas in the bulb may take a moment to be fully ionized and begin emitting light.

They turn off instantly because while it may take a moment for the control circuitry and/or the gas in a CFL lamp to turn on, removing the power turns everything off instantly.

Anonymous 0 Comments

That happens in neon lamps. There’s gas in those tubes and when you turn on the light electrons move around and hit each other. This causes them to release photons (light). The time between turnşng on the switch and getting light is the time it takes for those atoms go get moving. They stop immediately when you turn off the switch.

Anonymous 0 Comments

Traditional “incandescent” light bulbs would turn on pretty much instantly. But we’re replacing them more and more with different types of bulb like fluorescent and LED. Fluorescent tubes and LEDs aren’t powered directly from the house’s wiring – instead, there’s a circuit called a “ballast” (in fluorescents) or a “driver” (in LEDs). These circuits tend to use at least one or two decently sized “capacitors”. To do their job. A “capacitor” is an electrical component that stores a small amount of electrical energy. Capacitors can be used for a handful of purposes, one of which is to smooth out the voltage in a circuit. Either way, since they store a bit of energy, they take a moment to build their charge, hence the delay.