system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 why the light on my Dell AC Adapter doesn't go out immediately after unplugging it.

Sometimes electricity "goes away" the instant I unplug whatever it is that was being powered.  Other times, it appears to hang around for a few seconds.  

For example, when I unplug my television or vacuum, it turns off instantly.  When I unplug my dell laptop AC Adapter, yes, the computer stops being powered instantly, but there is still some small amount of power that keeps the light on at the tip of the plug illuminated for about 5 seconds or so.  Why?
gpt
Let's imagine that you have a small water mill and a glass. If you use the glass directly on the water mill, the water mill will not turn regularly because you need to refill your glass with water.  
Now, let's use a funnel between your glass and your mill. You are now able to run your mill. (Most of sand mill toys are designed with this funnel!)  
When you stop filling your funnel, it takes some seconds for the funnel to empty.  
The glass is more or less your AC power, the funnel is a capacitor, the stream of water is DC power, and the mill is your led.