Magnetic field = the area around an object where a magnetic force can be measured - shown using field lines
Bar magnet - magnetic field lines
Direction of field line is always north to south (arrows point north to south).
The strength of the field is shown by spacing of the field lines - if they are close together, the field is stronger than when they are further apart.
Current flowing through a wire will create a magnetic field - long straight wire will create a circular magnetic field.
The direction of the current determines which way round the circle the field goes.
Rule - Right-hand grip:
Grip wire with thumb pointing in direction of current.
Fingers wrap in direction of field.
STRAIGHT WIRE
Strongest field closest to the wire.
STRAIGHT WIRE
Current controls strength and direction of field - larger current will create a stronger field but changing direction of the current will reverse the direction of the field.
A solenoid (long coil of wire) will create same field as bar magnet.
Solenoid or coil
SOLENOID OR COIL
Field is the strongest inside coiled wire.
SOLENOID OR COIL
Current controls strength and direction of field - larger current will create stronger field, changing direction of current will reverse the direction of the field.
SOLENOID OR COIL
More turns on the coil will also create a stronger field.
