Magnetism

• The magnetic field strength is determined by the current flowing through a wire coil and is directly proportional to it.
• Like poles repel and unlike poles attract.
• A compass needle is attracted to the north end of a bar magnet, indicating that it has a south pole at its north end.
• Magnetic fields exert forces on other magnetic fields and on moving charges such as electrons.
• Magnetic fields emanate from moving charges such as electric currents.
• Magnetic fields can exert forces on other magnetic objects or on electric charges moving through the field.
• A solenoid is a long, thin coil that can be used as an electromagnet when connected to a battery or other power source.
• When a magnet is placed near another magnet, they attract if their poles are opposite (N-S) and repel if their poles are similar (N-N or S-S).
• A compass needle can be used as an indicator of magnetic fields, with its north pole pointing towards the south end of a magnet or bar magnet.
• Magnetic fields can be created around wires carrying electric currents.
• Moving magnets produce electricity due to their motion relative to a stationary object with free electrons (Faraday's Law).
• Electric currents can be used to create magnets or change their orientation.
• The strength of the magnetic field inside a solenoid depends on the number of turns of wire in the coil and the amount of current flowing through it.
• When a permanent magnet is placed near a solenoid with no current passing through it, there will be no force between them because there are no like poles close together.
• Magnetic fields always move from north to south.
• an electromagnet is a coil of wire that acts as a magnet when a current is passed through it also called a solenoid
• strengths of permanent magnets cannot be changed, but can be amplified by: Increasing current, number of turns in wire and adding a magnetic material as a core
• Electromagnets can be switched on and off
• the magnetic field can be reversed if the current is reversed, and the magnet is placed in the opposite direction