What is circuit

In order to provide power, circuits must be closed. This happens when a complete loop is formed from one side of the voltage source to the other side. If there are any interruptions in this loop, the electrons cannot complete their loop, creating an open circuit. When the conductive path of a circuit connects directly from one end of the voltage source to the other without first powering a load, the result is a short circuit. Photo Credit: Dummies. Current flows everywhere it can, and if it can find a shorter path, it will take it.

This is why conductive wires are coated in an insulator - to prevent accidental short-circuiting through wires touching. Short circuits can be very dangerous and cause wires to burn up, damage the power supply, drain the battery, start a fire and more. This is exactly like the balloon: the pressurized air in the balloon wants to flow from inside the balloon higher pressure to outside the balloon lower pressure.

If you create a conductive path between a higher voltage and a lower voltage, electricity will flow along that path. And if you insert something useful into that path like an LED, the flowing electricity will do some work for you, like lighting up that LED.

So, where do you find a higher voltage and a lower voltage? Here's something really useful to know: every source of electricity has two sides. You can see this on batteries, which have metal caps on both ends, or your wall outlet that has two or more holes.

Why does every source of electricity have two sides? In any power supply, the positive side will have a higher voltage than the negative side, which is exactly what we want. In fact, when we measure voltage, we usually say that the negative side is 0 volts, and the positive side is however many volts the supply can provide. Electrical sources are like pumps. Pumps always have two sides, an outlet that blows something out, and an inlet that sucks something in.

Batteries and generators and solar panels work the same way. Something inside them is hard at work moving electricity towards the outlet the positive side , but all that electricity leaving the device creates a void, which means that the negative side needs to pull electricity in to replace it.

We're finally ready to make electricity work for us! If we connect the positive side of a voltage source, through something that does some work such as a Light Emitting Diode LED , and back to the negative side of the voltage source; electricity, or current , will flow. And we can put things in the path that do useful things when current flows through them, like LEDs that light up. This circular path, which is always required to get electricity to flow and do something useful, is called a circuit.

A circuit is a path that starts and stops at the same place, which is exactly what we're doing. Click this link to see a simulation of current flowing through a simple circuit.

This simulation requires Java to run. However, Franklin had no way of knowing that electrons actually flow in the opposite direction - at the atomic level, they come out of the negative side and loop back to the positive side.

Because engineers followed Franklin's lead for hundreds of years before the truth was discovered, we still use the "wrong" convention to this day. Practically speaking this detail doesn't matter, and as long as everyone uses the same convention, we can all build circuits that work just fine.

The reason we want to build circuits is to make electricity do useful things for us. The way we do that is by putting things in the circuit that use the current flow to light up, make noise, run programs, etc. Knowing about these will help tremendously when you're troubleshooting your own circuits.

This is a very bad idea. This seems like the best possible circuit, so why is it a bad idea? Remember that electrical current wants to flow from a higher voltage to a lower voltage, and if you put a load into the current, you can do something useful like light up an LED.

In computing, the term "circuit" is used more liberally and may be used to reference a circuit board or an integrated circuit. The internal workings of computers and other electronic devices are comprised of these components , which may each contain hundreds or thousands of individual circuits.

The large number of circuits inside computers allow them to route data to different locations and perform complex calculations. These processors contain logic gates that can rapidly open and close circuits. Modern processors have so many circuits and transistors, they can perform billions of instructions every second.

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