Chapter 7 Magnetism

7-1 – Magnetism Magnetism – Magnetic forces – Magnetic poles produce magnetic forces Forces based on Strength of magnets Distance between magnets Like poles repel; opposite poles attract

7-1 - Magnetism Magnetic field – Direction of field Lines closer together versus farther apart Why does magnetic field produced?

7-1 - Magnetism Magnetic Field Direction Always points away from north pole toward south pole

7-1 - Magnetism Earth’s Magnetic Field Earth’s magnetic poles are opposite to Earth’s geographic poles What generates the Earth’s magnetic field?

7-1 - Magnetism What makes a magnet? Magnetic domains – Permanent magnets vs. temporary magnets

Magnetic poles cannot exist by themselves; north pole must have a south pole

7-2 – Electricity and Magnetism Electric Current and Magnetism Electric current creates a magnetic field Direction of current affects direction of magnetic field lines Increasing current increases the strength of magnetic field Magnetic field decreases as you move away from the wire

7-2 – Electricity and Magnetism Electromagnetism- Electromagnetic force – Electromagnets Changing the shape of a current carrying wire changes the magnetic field Forms a solenoid More loops in solenoid, stronger the electromagnet

7-2 – Electricity and Magnetism Electromagnetism- Electromagnetic force – Electromagnets Changing the shape of a current carrying wire changes the magnetic field Forms a solenoid More loops in solenoid, stronger the electromagnet

7-2 – Electricity and Magnetism Making an electromagnet rotate Uses the magnetic field generated by current and the change in polarity

7-2 – Electricity and Magnetism Using Electromagnets Speakers Galvanometers Electric Motors

7-2 – Electricity and Magnetism Electric Motors See figure 15 on page 214 Uses the flow of current to change the poles of the electromagnet

7-3 – Producing Electric Current Electromagnetic Induction - Uses a magnet to create electric current Changing magnetic field

7-3 – Producing Electric Current Generators- Uses electromagnetic induction Turns mechanical energy into electrical energy

Motors and Generators Different sides of same coin Motor = electrical energy in, mechanical energy out Generator = mechanical energy in, electrical energy out

7-3 – Producing Electric Current Direct Current and Alternating Current Direct Current (DC) – Alternating Current (AC) –

7-3 – Producing Electric Current Transformers Reduces voltage without changing amount of electrical energy