Sadly, in the event of a string of lights going out on your tree, replacing the strand is usually the best option. It's pretty difficult to find that one bulb that's causing the problem. However, this is a great time to look at the difference between series and parallel circuits. Just about the simplest circuit you can create uses just one battery and one light bulb.
In one fun activity, you can give a person one wire, one battery and one light bulb. Ask the person to make the bulb shine.
It's possible to get it to work, but it can still cause some trouble for people. In order to get the bulb to glow, you need a complete circuit. There has to be a path for the current to come out of one end of the battery, go through the filament in the bulb and then return to the battery.
Here's how that could work. When current passes through the filament, it makes the filament get super hot. Super hot things glow. That's all the bulb does. But why the glass on the outside? That is there to keep air away from the super hot filament.
With air in contact with the filament, it would burn out. If you take away any one of the parts for the complete circuit, there would be no current and no glowing bulb. Now you want to connect two light bulbs to battery. Here is one way you could do that. In this case, there is just one path for the current to follow. The current that goes through the first bulb also goest through the second bulb.
If you remove any part of this circuit like take out a bulb , everything goes out. If you wanted, you can make a similar circuit with 10 or 20 bulbs.
Just connect them all in a line so that the same current goes through each one. This is a series connection. The difference in this circuit is that each lightbulb has its own "path" to the battery.
If you break one of these bulbs, it doesn't really do anything to the other bulb. Here is a quick demo showing the difference between bulbs in series and bulbs in parallel. View Iframe URL. Oh, and just like the lightbulbs in series you can do this with many, many bulbs. Fuses are important safety features for many electrical appliances, but most of us don't even know that they're there.
In holiday lights, the fuse can be found near the part of the strand that plugs into the wall, often called -- and I'm not making this up -- the male end of the wire. Normally, the fuse is accessible through a small plastic door in the plug that can be opened and closed for replacing the fuse.
As the electrical current within a wire increases, the wire can heat up, at times causing melting or even fires. When the current increases past a safe level, instead of the wire melting or your Christmas tree catching fire, the fuse safely opens the circuit, averting many disastrous scenarios. Fuses are typically small sections of replaceable wire, rated to a maximum current level. Because they are more delicate than the rest of the wiring, a fuse will burn out before overcurrent has an opportunity to overheat other portions of the light strand.
When a fuse breaks, the circuit becomes incomplete and current cannot flow through the remainder of the circuit. LED holiday light strands are becoming more popular. On top of that, they are significantly less likely to burn out or break compared to their incandescent forerunners. Why is this? While incandescent light technology is relatively straightforward a heated filament glows much like any ember in a fire , the mechanics of LED lights are much more sophisticated.
When current is applied to the system, electrons from the negative side move toward the positive side. When an electron and an electron hole collide, a small amount of energy is released as a photon. The result is the visible light we see in an LED. LEDs are wired in series-parallel just like the traditional bulbs we described above.
Unlike incandescent lights, however, LEDs do not typically make use of shunts. This homeowner shows off his Christmas decorations. They consume a lot of power. If you have a strand of 50 5-watt bulbs, the strand consumes watts! Consider that most people need two or three strands to do a tree and five or 10 strands to do a house and you are talking about a lot of power!
Because the bulbs consume so much power, they generate a lot of heat. When used indoors, three strands at watts per strand are generating as much heat as a watt space heater!
The heat from the individual bulbs can also melt things. They are expensive. For light strings that commonly have over 50 bulbs, they are constructed in 2 or more continuous circuits.
If a bulb is missing in a circuit only the bulbs in series of it will go out. The solution: Visually inspect each bulb in the part of the Christmas light string that is out. Check for any bulb that is missing or partially unseated from the socket and if you find a space or wonky bulb, replace the bulb with one of the two extra bulbs that hopefully were included with your light set or gently push the bulb back into its socket.
The rating of the light string was exceeded and the bulbs blew out the wire at the base of each bulb that is supposed to conduct electricity. Visually check the part of the light string that is out and replace any smoked bulbs. There is an issue with the wiring harness and the copper wire is broken in the string.
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