# Resistance

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A series of free GCSE/IGCSE Physics Notes and Lessons.

Resistance

In this lesson, we will
• Describe what is meant by a resistance.
• Calculate resistance in a circuit.

An electric current is a flow of electrons through a conductor such as a metal wire. As they move, electrons collide with atoms in the metal. Electrical energy is transferred into other forms e.g. thermal. The resistance tells us the potential difference required to drive a current through a component. The resistance of an electrical component can be found by measuring the electric current flowing through it and the potential difference across it.

The following diagram gives the formula for resistance, voltage and current. Scroll down the page for more examples and solutions on how to use the formula.

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