How do cords work

If you cut one open, it might look something like this. In this case, you can see that there are actually 5 wires inside one usb cable. It's not just a single wire. To light the bulb, I just need to pick two of these wires so that I can make a complete circuit with the battery and let current flow through the filament.

It's a little messy, but here's what it looks like. Basically, I am using two wires inside of this cable. But because I can't connect the usb plug to the battery, I have to use some extra wires.

Oh, sure—I could cut off the plug end of the cable and remove the plug part. However, then it wouldn't look like I'm still using a cable. There's a reason I'm writing about the difference between cables and wires. I think many students in physics labs confuse these two things. They are so used to cables, they sort of forget about complete circuits.

This is particularly obvious when students try to use a multimeter to determine the voltage or current in a circuit. Suppose I want to use a voltmeter to measure the voltage across the light bulb in a simple circuit. If the wire from the voltmeter were to be considered a phone cable, you would connect it like this. But this doesn't work. The voltmeter, like just about every electrical measuring device, needs to have a complete circuit. You need two wires to measure voltage. Here's what it should look like.

Those thick wires from the voltmeter might look like cables, but they are in fact just wires. You need two wires to make a complete circuit. Rhett Allain is an associate professor of physics at Southeastern Louisiana University. He enjoys teaching and talking about physics. Over-heating has the potential to cause failure of the insulation material resulting in current short circuiting, electric shock, or fire.

Return to FAQs. How do electrical cables work? Other questions How is electricity generated from Biomass? The amount of current which can effectively flow through the electrical cable will be determined by a combination of factors: the cross-sectional area of the conductor the resistance of the conductor material the insulation material the installation method or environment.

The Cable Lab. It is a legal requirement for all new circuits originating at the switchboard and supplying lighting or socket outlets power points in domestic buildings to have RCD protection.

These RCDs will normally be located at the switchboard. They will provide protection for all electrical wiring and appliances plugged into new circuits. You can test your socket outlet and portable RCDs by plugging in a small electrical appliance such as a night-light :. However, be aware that tripping circuits will turn off the power to any appliances on that circuit. So appliances with electronic clocks will have to be reset. If your RCD trips at other times; note the appliances connected at the time, unplug all connected appliances and reset the RCD, plug in the appliances one at a time and switch on.

If the RCD trips when an appliance is switched on, the appliance should be repaired or replaced. If the RCD does not trip when appliances are plugged in and switched on, one at a time, but trips when several appliances are used together, you should get your RCD checked by a licensed electrician.

An isolating transformer protects you from an electric shock by providing an electricity supply that is isolated from earth. For maximum protection, the transformer should be placed as near as possible to the electrical outlet. Socket outlets fitted with internal protective shutters make it more difficult for children to poke things into them.

Recessed sockets and shrouded plugs on electrical fittings, extension cords and double adaptors help to prevent contact with the metal pins on a plug if they become partially exposed. An additional safety feature is a plastic insulation sleeve on the metal pins on a plug. Like recessed sockets, these prevent contact with the metal pins while connected to electricity supply.

The pins of insulated pin plugs should be inspected for damage to the insulation of the pins, and, if fitted, the shroud on cord extension sockets. We recommend that you use appliances fitted with moulded plugs that do not need rewiring.

However if you do need to rewire, there is only one way to wire an electrical plug safely. Study the diagram below and ensure that you always connect the correct colour to the correct letter. In New Zealand, it is most common for the coloured wires inside power cords to look like either A or B. They should be connected as illustrated below. If you are rewiring a plug yourself, always ensure the wires are correctly positioned, as this is a common cause of serious electric shocks if wired incorrectly.

All household power outlets in New Zealand only use a flat three or two-pin plug, depending on whether an earth connection is fitted. Last updated 4 September at Safe living with electricity Cords and plugs. How to decide what work requires a vaccinated employee and WorkSafe's enforcement approach.

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