# What is electric

## What is electric current?

### The basic principle of electric current

The inside of the flashlight can be imagined as a circuit: the battery is connected at one point by a cable to the light bulb at the front. From there another cable leads back to the battery. The electrons now migrate from one point on the battery through the cable and the light bulb to the other, and a current flows.

But what makes the electrons move so tirelessly through the cable? To do this, one has to take a closer look at the structure of an atom. The nucleus of the atom is made up of neutrons and positively charged particles, the protons.

The shell of the atom consists of negatively charged particles, the electrons, which float around the nucleus. If you now remove electrons from an atom, a positively charged particle remains: the cation.

But neither the electron nor the cation like this separation. Both are constantly trying to return to their original, balanced state.

There is now a point on the battery where a shortage of electrons is created: the positive pole. The opposite applies to the negative pole: an excess of electrons is produced. Electrons are therefore repelled at the negative pole and pushed to the positive pole.

A stream flows. The principle on which electric current is based is the ability of the electrons to always strive for a neutral state. The current strength indicates how many particles move simultaneously through a conductor such as the cable and is measured in amperes (A).

### Electricity needs voltage

So that the current flow can be maintained and does not die as soon as the electrons reach the positive pole, electrons have to be removed again and again at the positive pole. This is exactly what the battery in the flashlight does with the help of chemical reactions.

You can imagine it as if some kind of pressure was built up in the battery. This pressure is created by the difference in the charges on the minus and plus poles: the voltage. It is measured in volts (V).

Voltage can also be present without a current flowing. The current, on the other hand, cannot flow without voltage: only the voltage between the plus and minus pole sets the electrons in motion.

But why does the movement of the electrons in a certain direction make the lightbulb in the flashlight glow? This is because the fine wire in the bulb is an obstacle for the electrons.

They build up at the "entrance" to the wire, but eventually have to squeeze through. In doing so, they rub against each other and produce heat. The wire in the lightbulb starts to glow and it becomes light.

### Direct current from the battery, alternating current from the socket

If we switch on a floor lamp in our living room that is connected to a socket instead of a flashlight, it works in a similar way. And yet the electricity from the socket is different.

The electrical current generated by battery-operated devices such as the flashlight is called direct current. Here the particles always move in the same direction and migrate from one pole to the other.

With alternating current from the socket, the electrons only move a little bit in one direction, then immediately again in the other direction. Plus and minus poles swap their functions in a fraction of a second.

In our power grid, for example, this happens 50 times a second. The advantage of alternating current over direct current is that less energy is lost during transmission.

In addition, it is easier to transform voltages with alternating current - for example from high voltage to low voltage networks in households.