Electromagnetism

This lesson covers how electric currents produce magnetic fields and how electromagnets work — as required by the Edexcel GCSE Physics specification (1PH0), Topic 8: Magnetism and Electromagnetism. You need to understand the magnetic field around a current-carrying wire, the right-hand grip rule, the field of a solenoid, and the factors that affect electromagnet strength.

---

Magnetic Field Around a Current-Carrying Wire

When an electric current flows through a wire, it produces a magnetic field around the wire. This is one of the most important discoveries in physics — it links electricity and magnetism.

Key Facts

• The magnetic field around a straight wire forms concentric circles centred on the wire.
• The field is perpendicular to the wire (at right angles to the direction of current).
• The field lines are closer together near the wire (stronger field) and further apart as you move away (weaker field).
• Reversing the current reverses the direction of the magnetic field.
• Increasing the current makes the magnetic field stronger (field lines closer together).