Voltage, Current, and Resistance

Think of a circuit like plumbing. Voltage is the water pressure — it pushes electrons through the wire. Current is the flow rate — how many electrons pass a point each second. Resistance is a narrow pipe — it restricts flow and turns electrical energy into heat or light.

• Voltage is measured in volts (V) — a wall outlet is 120V or 230V depending on your country
• Current is measured in amperes (A) — your phone charger draws about 1–2A
• Resistance is measured in ohms (Ω) — an incandescent bulb has a few hundred ohms when hot

These three are locked together by Ohm's Law (V = IR), which the next lesson covers in depth.