# Lesson 01: Fundamentals of electricity

1. Learn the basic magnitudes used to measure electricity
2. Know why and the way in which electricity flows.
3. Recognize the difference between dangerous and innocuous experiments.

### This is a basic lesson

No previous knowledge is requiered.

If you find it too easy, move on to the next lesson, or check our basic tutorials on electronics here.

## What is electricity and why does it flow?

You can think of electricity as tiny particles moving through mass. Jumping from atom to atom. Those continued and quick jumps are known as current flow, and the small particles, are called electrons. Electricity flows through mass for the a reason similar to that of water falling from the sky when it rains. Each water droplet, at a certain height, has what is known as potential energy (which equals to $E_p=mgh$). Potential energy is formally defined as the energy difference between two object or the energy that one object has with respect to another one (see resource #1 for further information).

Universe tends in general to lower energy states. That means that, for instance, water falls from the sky (and doesn’t stay up there) because when it has fallen it will have less energy ($E_{p_2} = E_{p_1} – m·g·fall_{distance}$) than before. When a ball falls off the roof, it is for that exact reason. When an electron jumps from one atom to the following one, it is, once again, for that reason.

## How do we measure electricity?

To answer that question we have to describe first the two most important and basic magnitudes of any electrical current: voltage and current. In the international system of units (SI), the former is measured in Volts (V), and the latter is measured in Amperes (A), and often shortened as “amps”.

The voltage indicates “how energetic” are those electrons, and the current indicates “how many are there per second and section”. To continue with our mass analogy, we could say that when if we threw pianos from a rooftop, the voltage would be equivalent to the height of the bulding, and the current to the number of pianos thrown that go through the second floor in one second.