Lesson 6 of 9

Resistance

Goal: Calculate resistance.

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Resistance tells you how hard it is for current to flow through a part of a circuit.

resistance (Ω) = potential difference (V) ÷ current (A)

  • Resistance is measured in ohms (Ω).
  • More resistance means less current, if the potential difference stays the same.
Rows of wires glowing orange inside a toaster
Resistance makes things warm. When a current flows through a part with resistance, energy is transferred to the surroundings. The wires in a toaster get hot enough to glow.

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Key words in this lesson

Current A flow of electric charge

Potential difference The push that makes charge flow

Resistance How hard it is for current to flow

Ohm The unit of resistance

For teachers: AQA 3.2.1 · Pearson Edexcel 35.1, 35.2 · Cambridge 9Pe.03