Magnetic fields in a wire
When a current flows in a wire, it creates a circular Area surrounding a magnet that can exert a force on magnetic materials. around the wire. This magnetic field can To cause something to change direction. the needle of a magnetic compass. The strength of the magnetic field is greater:
- closer to the wire
- if the current is increased
Magnetic fields around a wire carrying an electric current
Solenoids
A A straight coil of wire which can carry an electric current to create a magnetic field. consists of a wire coiled up into a spiral shape. When an electric current flows, the shape of the magnetic field is very similar to the field of a bar magnet. The field inside a solenoid is strong and uniform. The small magnetic fields caused by the current in each coil add together to make a stronger overall magnetic field.
A solenoid, shown here in cross section, has a stronger electromagnetic field than
a single straight wire
