Why is electricity important 4

What is electricity

The question "What is electricity?" is explained in a simple way in this article. Summary of the content:

  • A Explanationwhat the electric current is.
  • Lots Examples around the electric current.
  • tasks / Exercises to the electric current.
  • A Video, which deals with the electric current and the amperage.
  • A Question and answer area around this basic concept of electrical engineering.

This article is part of our electrical engineering course "From the basics of electrical engineering in 5th grade to becoming an engineer".

Explanation: Electricity simply explained

In the basics of electrical engineering you learn that there are electrical charges. There are positive electric charges and negative electric charges. This leads us to the electric current.


Electric current is the directional movement of electric charge carriers. In school this is usually referred to as the movement of electrons.

Just imagine this as if electrons were flowing through a wire.

We now have the question "What is electricity?" simply clarified. It's just not that easy with electricity. Because there are prerequisites for a current to be able to flow at all.

In most cases, electrical currents flow in closed circuits. A closed circuit normally includes

  • at least one electrical source
  • at least one device or component
  • which are connected with lines

The next graphic shows a circuit with a glowing lamp (yellow), wires and on the far left is an energy source (the two dashes).

The graphic shows one closed circuit. The opposite of this is an open cycle. In this case, the line is interrupted, either by a switch or, for example, by cutting the lines. In one open circuit no electricity flows.

How much electricity is flowing?

How tall a person is is usually given in meters. A person's weight is often given in kilograms. But in what do you state the current? There is also the ampere, abbreviated with an A. That brings us to the electrical current strength.


The electrical current indicates how much electrical charge moves through a conductor per second. The unit is the ampere (A). In formulas, the electric current is used for a capital I.

Knowing this, one can almost assume that one can calculate the electric current by calculating the charge per time. The formula is:

Or in words:

Note: The formula is sometimes written with delta values. However, this is too difficult for newcomers to electrical engineering. Therefore, I have renounced it here.

There are numerous other formulas to calculate the electrical current strength. I would therefore like to briefly mention another one here. First there is the formula that belongs to Ohm's law. In this case, two terms appear that we should briefly mention here (and will be discussed in more detail in the next articles).

  • tension: The electrical voltage indicates how strong the "drive" of the current is. The more voltage there is, the more current can flow. The voltage "pushes" the charges through the line, somewhat colloquially expressed. Voltages are given in volts - V for short.
  • resistance: The electrical resistance, however, hinders the movement of the charge. The higher the resistance, the less current. Resistances are given in Omega - Ω for short.

As you can see, tension and resistance oppose each other. How much current flows depends on both variables. The following applies:

Or in words:

We now know the formula for calculating the current, or rather the electrical current strength. Examples are given in the next section. Before that, however, briefly the difference between direct current and alternating current:

  • Direct current: A direct current is an electrical current whose strength and direction does not change over time. In other words: the current only flows in one direction and always with the same strength.
  • Alternating current: Alternating current refers to an electric current that changes direction in regular repetition. The electric charges move alternately in one direction and then again in the other direction. As if you were driving your car up and down a street over and over again.

Examples of electric current

In this section we will deal with a few examples relating to electrical power. Some of these are pure word problems, and some are arithmetic problems on this topic.

example 1:

List some electrical devices that use electricity.


There are a lot of electrical devices. A couple of examples would be:

  • fridge
  • TV
  • Pc
  • Smartphone / cell phone
  • Hairdryer
  • Washing machine
  • air conditioning
  • coffee machine

Example 2:

A constant current of 2 amperes is present over a period of 4 seconds. Calculate the electrical charge.


We first convert the above equation to Q. Then we use 2 amps for I and 4 seconds for t. If we multiply "2" by "4" and "A" by "s" we get 8 As. We still simplify: 1 ​​As = 1 C, therefore 8 As = 8 C.

Example 3:

We have a voltage of 6 volts and a resistance of 2 ohms. How much electricity is flowing?


We take the formula from above, which shows the relationship between current, voltage and resistance. Here we use 6 volts for the voltage "U" and 2 ohms for the resistor R. This gives us the current at 3 amps.

Tasks / exercises on electricity


Electric power video

Basics of electrical engineering

The basics of electrical engineering are covered in this video. First of all, it deals with basic terms such as current, voltage and resistance. Their connection via Ohm's law is also dealt with. A simple circuit is then dealt with. With this it can happen from time to time that there is more than 1 resistance. Therefore, the grouping of resistors is also shown.

Next video »

Questions with answers electric current

In this section we will look at questions and answers about electricity.

Q: When was electricity discovered and when was it used technically for the first time?

A: Nobody really knows. However, it is said that as early as the 6th century BC Thales of Miletus discovered that amber attracts other bodies. However, a lot of time passed before the first "real" technical use. For example, the use of telegraphy did not begin until the 19th century.

Q: Is electricity dangerous?

A: You should always be careful when using electricity. The human body conducts electricity. With very small currents, nothing usually happens here. Larger currents, on the other hand, can seriously injure or even kill people. Therefore, for example, you have to be very careful when working on the socket in the house. In the event of improper use, currents can flow through people, which are fatal.

Q: What other topics should I check out?

A: For the basics of electrical engineering and magnetism, you should still have a look at these topics: