1. Electricity – what is it?
From moving electric charges to batteries, rechargeable batteries, and essential safety rules.
What is electric current?
Electric current is the directed movement of electric charge. In metal wires, it is mainly electrons that move. You can imagine many tiny particles being pushed through a conductor.
Electric current is invisible, but we can observe its effects: light, heat, movement, or magnetism.
⭐ Knowledge question
What moves through a metal wire?
How is electricity generated?
Generator
Motion and magnetic fields generate voltage, for example in a power station, wind turbine, or bicycle dynamo.
Solar cell
Light releases charge carriers in a semiconductor and thereby generates direct current.
Chemical cell
Chemical reactions separate charges in batteries and rechargeable batteries.
No movement yet – no voltage.
⭐ Knowledge question
Which machine converts motion into electrical energy?
Direct current
Direct current (DC) flows continuously in the same direction. Batteries, rechargeable batteries, solar cells, and USB ports provide direct current.
⭐ Knowledge question
What characterises direct current?
Alternating current
Alternating current (AC) changes direction regularly. The European power grid operates at about 230 volts and 50 hertz. 50 hertz means 50 complete cycles per second.
⭐ Knowledge question
What does 50 hertz mean?
Volts, amperes, watts, and hertz
Volt (V)
Voltage is the “driving force” for charge, similar to pressure in a water pipe.
Ampere (A)
Current describes how much charge flows per unit of time.
Watt (W)
Power indicates how quickly electrical energy is converted. For direct current, approximately: watts = volts × amperes.
Hertz (Hz)
Frequency tells us how often a process repeats each second.
Power: 3.0 W
⭐ Knowledge question
Which unit is used for electrical power?
When is electricity dangerous?
Important: mains electricity is never an experiment!
The danger depends not only on voltage, but also on the current through the body, its path, duration, frequency, skin moisture, and surroundings. Even small currents can cause muscle spasms; higher currents can disrupt breathing and heart rhythm. Wet skin lowers resistance, which is why water is especially dangerous.
Children should only use purpose-built, touch-safe battery or educational kits with extra-low voltage and adult supervision. Sockets, mains-powered devices, exposed cables, and meter cabinets are strictly off limits.
Emergency
Never touch a person who may still be in contact with electricity. Switch off the power, keep your distance, and call 112. Even after an apparently minor electric shock, an adult should seek medical advice.
⭐ Knowledge question
Why is wet skin more dangerous?
Battery and rechargeable battery
Battery
A battery converts chemical energy into electrical energy. In everyday language, “battery” often means a non-rechargeable primary cell.
Rechargeable battery
A rechargeable battery can be recharged. During charging, electrical energy is stored again as chemical energy.
Battery: ██████████
Rechargeable battery: ██████----
⭐ Knowledge question
Which energy store can normally be recharged?