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So why aren't the bulbs hooked up in parallel?
Draws too much current. Older strands used to be parallel and were a frequent cause of fires. LEDs use less power but don't work well in parallel.
I thought those christmas lights had bee replaced by led strips.
Even LEDs need electricity, and electricity can be delivered to them serially or in parallel too.
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Huh? Why not just use two wires and connect one wire to the other with each bulb. Like this: http://www.planetchristmas.com/Images/MinisA.gif I think the real answer is that if you did it this way (in traditional pre-transformer light sets), each bulb would have to be rated for 120v, or whatever your local line voltage is, which would make them both more expensive, and more dangerous.
Interesting: That would suggest that if you let enough bulbs on a strand go out, you reach a cascading-failure threshold at some point, where the voltage across the remaining filaments is higher than their rating. And then I guess the breaker trips.
Edit: Sorry, I misread, I thought this subthread was about parallel circuits.
Earlier quoted context omitted.
Interesting: That would suggest that if you let enough bulbs on a strand go out, you reach a cascading-failure threshold at some point, where the voltage across the remaining filaments is higher than their rating. And then I guess the breaker trips.
That's not how parallel circuits work. The voltage is independent of how many devices are connected. That's how your wall plugs always provide 110V. Edit: Sorry, I misread, I thought this subthread was about parallel circuits.
If half of them burn out (and, as the article explains, become a short-circuit), then you have 50 bulbs, and each is getting 2.2V across it.
Earlier quoted context omitted.
Draws too much current. Older strands used to be parallel and were a frequent cause of fires. LEDs use less power but don't work well in parallel.
Interesting. And your theory seems to hold water: V=IR, so with constant voltage, current is inversely proportional to resistance, and the resistance of 100 bulbs in series is far far greater than 100 bulbs in parallel.
A truly appropriate article for a site whose name is "wired". LED sets are usually wired in series too, since they're current-driven devices.
Earlier quoted context omitted.
Interesting. And your theory seems to hold water: V=IR, so with constant voltage, current is inversely proportional to resistance, and the resistance of 100 bulbs in series is far far greater than 100 bulbs in parallel.
Your intuition is correct, but a minor nit: bulbs aren't linear devices and don't have a fixed resistance. At low power, a bulb will look pretty close to a short circuit (it's just a piece of tungsten wire, after all). As power increases, the filament temperature rises and so does its resistance. This is why bulbs generally burn out when turning on - 170V across a mostly short circuit, with most of the resistance bei…
Curious to know what would happen if 2 or more bulbs broke at the same time?