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Circuit FoundationsšŸ”—

Every circuit is a push, a flow, and something in the way. This topic builds those three ideas from the atom up, then uses them on everything that follows: power and heat, faults and fuses, alternating current, magnetism, and the two components that store energy.

Each article stands on its own, but they're written to be read in this order, and each one ends by pointing to the next. No prior knowledge is assumed anywhere. If you're studying for the Canadian amateur radio Basic exam, Start Here on Exploring Radio shows which of these articles each exam topic draws on.

Circuit Foundations reading order, as a transit map One line snaking through fourteen stops in five stages. What electricity is made of: Conductors, What Is Electricity?, Prefixes; The three quantities: Voltage, Current, Resistance; Putting them to work: Ohm's Law and Power, Opens, Shorts, and Fuses; Beyond steady DC: AC vs DC, Magnetism; Combining and storing: Series and Parallel, Voltage Dividers, Capacitors, Inductors. Every stop is a link to its article. Click any stop to open its article What electricity is made of The three quantities Putting them to work Beyond steady DC Combining and storing 1. Conductors 1 Conductors 2. What Is Electricity? 2 What Is Electricity? 3. Prefixes 3 Prefixes 4. Voltage 4 Voltage 5. Current 5 Current 6. Resistance 6 Resistance 7. Ohm's Law and Power 7 Ohm's Law and Power 8. Opens, Shorts, and Fuses 8 Opens, Shorts, and Fuses 9. AC vs DC 9 AC vs DC 10. Magnetism 10 Magnetism 11. Series and Parallel 11 Series and Parallel 12. Voltage Dividers 12 Voltage Dividers 13. Capacitors 13 Capacitors 14. Inductors 14 Inductors
The reading order as one line. Every stop is a link, and the numbers match the list below.

1. What Electricity Is Made OfšŸ”—

2. The Three QuantitiesšŸ”—

  • Voltage ā€” energy per charge, always measured between two points
  • Current ā€” charge per second, the same all the way round a loop, and the quantity that hurts
  • Resistance and Conductance ā€” what sets a wire's resistance, tolerance, and why a long extension cord gets warm

3. Putting Them to WorkšŸ”—

4. Beyond Steady DCšŸ”—

  • AC vs DC ā€” current that reverses sixty times a second, sine waves, and what "120 V" really means
  • Magnetism and Electromagnetism ā€” fields, electromagnets, induction, and transformers

5. Combining and StoringšŸ”—

  • Series and Parallel Circuits ā€” the two ways every circuit is wired, and what each does to voltage and current
  • Voltage Dividers ā€” two resistors that make any voltage you need, and why the output sags under load
  • Capacitors ā€” storing charge, the RC time constant, and how a camera flash makes 15 kW from two AA cells
  • Inductors ā€” coils that resist change, and how a 12 V battery fires a spark plug at 40 kV

What You'll Take AwayšŸ”—

  • The vocabulary

    Volts, amps, ohms, watts, farads, and henries, and the prefixes that scale them.

  • The arithmetic

    Ohm's law, power, series and parallel, and time constants, worked with real values.

  • The judgement

    How much current is safe, why a part gets hot, and what a fuse or a flyback diode is for.

  • The ground for everything else

    Components, microcontrollers, and power all build on this topic.

Where to StartšŸ”—

New to electronics? Start at the atom with Conductors, Insulators, and Semiconductors. If you'd rather see the whole picture first, What Is Electricity? covers it on one page and links into each deep dive.