Electrical Fundamentals

Voltage, current, power and the laws that tie them together. The language of electrical engineering. Learn what voltage, current, power and energy really are, how AC differs from DC, and the circuit laws and network theorems every other module is built on.

• Voltage — Voltage is the electrical 'push' — the energy each coulomb of charge gains or loses between two points. Learn potential difference, EMF, polarity, ground references and how real sources behave under load.
• Current — Current is the rate at which charge flows. Learn conventional vs electron flow, current density, how wires are sized, how current is measured and why a few milliamps through the body can be deadly.
• Power — Power is the rate of energy transfer. Master P = VI and its Ohm's-law forms, efficiency, power ratings, circuit loading and an introduction to AC real, reactive and apparent power.
• Energy — Energy is power accumulated over time. Learn joules and kilowatt-hours, electricity bills, battery capacity (Ah vs Wh), energy stored in capacitors and inductors, and how to size a battery bank.
• AC/DC — Direct current flows one way; alternating current reverses direction many times a second. Learn sine-wave parameters, RMS, phase and phasors, three-phase basics, and why the world runs on AC but increasingly uses DC.
• Circuit Laws — Ohm's law, Kirchhoff's current and voltage laws, and the series/parallel rules they produce. Learn to solve any resistor network with systematic nodal and mesh analysis.
• Network Theorems — Thevenin, Norton, superposition, source transformation and maximum power transfer — the shortcuts that reduce a complex linear network to something you can reason about in one step.