Magnetic Fields Around Wires and Solenoids

This lesson explains how an electric current produces a magnetic field around a straight wire and inside a solenoid (coil of wire), as required by the Edexcel GCSE Combined Science specification (1SC0). You will learn to predict the field direction using the right-hand rule and understand how to increase the strength of the field.

---

Magnetic Field Around a Straight Current-Carrying Wire

When a current flows through a wire, a magnetic field is produced around the wire. The field has the following properties:

Property	Detail
Shape	Concentric circles centred on the wire
Direction	Determined by the right-hand rule
Strength near the wire	Stronger (circles closer together)
Strength far from the wire	Weaker (circles further apart)

The Right-Hand Rule (Grip Rule)

To find the direction of the field around a straight wire:

1. Point your right thumb in the direction of the current (conventional current: positive to negative).
2. Your fingers curl in the direction of the magnetic field lines.