Area 02
Electrical circuits
How electric current flows, and how to control it
Electrical circuits power lights, phones and motors. Here you learn what makes current flow and how to use it safely.
What you will learn
- What voltage, current and resistance are
- Why a circuit must be closed for current to flow
- The difference between series and parallel connections
- Why components need the right current: not too little, not too much
Example experiments
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Light an LED and choose a resistor that keeps it safe.
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Connect two lamps in series, then in parallel, and compare their brightness.
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Add a switch and find where to place it to control the whole circuit.
Things you can build
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A torch with a switch
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A night light
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A simple alarm with a buzzer
These examples show the kind of work in this area. The published lessons may differ.
Try a small model
These small models run right here in your browser and keep working offline once the page has loaded. They are simplified teaching models, not the MEKALUMI simulation engine.
Keep the LED safe
Choose a battery and a resistor, then close the switch. With too little current the LED stays dark. With too much, a real LED could burn out.
- Current
- 11.4 mA
- LED
- Shining safely.
A resistor limits the current. Ohm’s law tells you how much: current = (battery voltage − LED voltage) ÷ resistance.
Model: ideal battery; red LED with a fixed voltage drop of 2 V, safe up to about 20 mA.
What the simulation simplifies
- Batteries and wires are often treated as ideal, but real batteries run down and real wires warm up.
- Simulated parts are identical; real parts differ slightly from each other.
Every simulation simplifies reality. Knowing how it does so is part of learning engineering.
Links to school subjects
Physics, mathematics (Ohm’s law), technology
Connections to other areas
Circuits lead on to digital logic, PCB design, automation and robotics.
Good to know
Virtual circuits are safe to explore. Electricity from wall sockets is dangerous: never experiment with it.