Unlike magnetic poles attract and like magnetic poles repel.
Permanent magnets: produce their own magnetic field.
Induced magnets: become magnetic when placed in a a magnetic field.
Magnetic field lines are always drawn from North to South.
Stronger magnetic field: draw more lines closer together.
Plotting compasses can show the shape and direction of the field of a magnet and the Earth’s magnetic field.
Place a magnet on a piece of paper and place a cross at one corner. Place a compass and trace where the needle points. Continue and then repeat from different starting points.
A current can create a magnetic effect around a long straight conductor.
The shape is similar to if you used your right hand and put your thumb up.
Strength of magnetic field: distance from wire and size of current.
A solenoid is an example of an electromagnet; a coil of wire with an iron core. They have the same magnetic field as a bar magnet.
F=BIl
Motor effect: a current-carrying wire produces a magnetic field. This interacts with the magnetic field of the permanent magnet. This causes a force. A split-ring commutator can be added to reverse the current at every half turn allowing the motor to continue spinning.