How to Build a Circuit Using Light Bulbs

Video Transcript

"Hi, I'm Steve Jones, and I'm going to tell you how to create a circuit using light bulbs. Now, in my circuit using light bulbs here is the bulb, and we have a symbol for a bulb which is a circle with a squiggle in the middle. We have a cell, and if we've got more than one cell we call it a battery, but this is a cell and that's the symbol for a cell; short line, long line, short line, negative, long line is positive. And we also probably need a switch or switches in which case, the switch has two connections and it is simply resem represented by that symbol. So, when we put together a simple circuit, this is a simple series circuit. Series indicates that the electricity goes once through every component, so you can see it just goes once around here. I have a switch, I have a cell, and I have a bulb. One thing to remember is if my cell has a voltage of 1.5 volts, as they usually do these small cells, then this lamp has also to have a 1.5 volt rating. This means that if you select a lamp which has a 12 volt rating it will not be very bright. It will be quite dim. If it has a half a volt rating when you connect it it's likely to burn out, because it'll get too hot, so you have to select the right voltage. If I take exactly the same circuit, still a series circuit, but this time I insert two bulbs in series in this way in fact the voltage from the cell will be shared between the two bulbs, and I'll get .75 volts on each if I've got 1.5 volts from the cell. So, if I use 1.5 volt cells for each of this these would be dimmer than in this case. This would be the correct brightness. These would be much dimmer. If I want to connect more than one bulb to the same power supply it can still be 1.5 volts, and these can be 1.5 volt bulbs. And in fact, I've got two circuits here. I've got this one, and I've got another one which goes through the bottom, and they are separate circuits and can be controlled by separate switches. They each have a voltage 1.5 volts, and will be as bright as this one providing of course that the cell is not asked to provide too much current. There's a maximum amount of current a cell will provide, and therefore they might not be quite as bright as in this case. So, that is, very simply, how you can create a circuit using light bulbs."