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Video transcription

Hi, I'm Steve Jones and I'm going to tell you how a solenoid works. Well first of all, what is a solenoid? It's very simple, it is a coil of wire. This is usually copper wire and as you can see here, it's coiled around like this, around some kind of former, this may be cardboard, it may be some other material, maybe plastic. Now the solenoid works because an electric current as you can see, an electric current indicated by these red arrows, flows through the wire that's provided by a power supply and a switch. So we can switch this electric on and off. This electric current creates a magnetic field. And if fact, this solenoid when it's switched on becomes a magnet. The solenoid, the work solenoid means just this coil of wire, but it becomes a magnet when the current is switched on. When it's switched off, it stops being magnetic. The more the current, the greater the current, the more powerful the magnet. Now for example in a car starter motor, there is a solenoid and as soon as the electricity passes through it, it connects a device which connects the starter motor and turns the engine. These solenoids are used everywhere, particularly in houses for cutting off the current if the current is too great. So if the current gets too big, the solenoid becomes a much more powerful magnet. Here, piece of iron and a spring and the iron is connected to the main circuit. So we've got a circuit out here and the main circuit is here and you can imagine that if this solenoid becomes very strong, a strong magnet, this iron will move away from this which is a solid fixed connection. That will break this circuit and that is called a circuit breaker. So a solenoid is a very simple device, a coil of wire, but it has many, many uses and nowadays you will find solenoids everywhere. Everywhere in your washing machine and in your home.