1. Lesson V “Electromagnetism” Matter & Energy

2. S.W.B.A.T. Explain how an electric charge creates a magnetic field Explain how an electric charge creates a magnetic field Describe how electromagnets are used Describe how electromagnets are used Relate electromagnets to everyday devices Relate electromagnets to everyday devices

3. Electricity & Magnetism Along with gravity and the strong & weak nuclear force, electromagnetism makes up one of the four known forces in the universe Along with gravity and the strong & weak nuclear force, electromagnetism makes up one of the four known forces in the universe Electricity & magnetism are two parts of the same force Electricity & magnetism are two parts of the same force

4. Electricity & Magnetism Hans Oersted (1820) discovered through experiments that electricity and magnetism were related Hans Oersted (1820) discovered through experiments that electricity and magnetism were related Oersted showed that electric current moving through a wire deflected a compass needle Oersted showed that electric current moving through a wire deflected a compass needle

5. Electricity & Magnetism Flowing electric charges create magnetic fields Flowing electric charges create magnetic fields Magnetic field lines form circles or loops around a flowing charge moving through a straight wire Magnetic field lines form circles or loops around a flowing charge moving through a straight wire

6. Electricity & Magnetism Electric charges moving through a magnetic field will be shifted 90 o from its direction of movement and from the magnetic field loop Electric charges moving through a magnetic field will be shifted 90 o from its direction of movement and from the magnetic field loop If the current flow is reversed the charges will shift 90 o in the opposite direction If the current flow is reversed the charges will shift 90 o in the opposite direction

7. “Right-Hand Rule”

8. Electricity & Magnetism If the current is moving parallel with the magnetic field loop then there is no deflection If the current is moving parallel with the magnetic field loop then there is no deflection Electric fields are different than magnetic fields in that it exerts a force on a charge in the same or opposite direction (+ or – charge) Electric fields are different than magnetic fields in that it exerts a force on a charge in the same or opposite direction (+ or – charge)

9. Electromagnets Looping a wire into a coil will create a combined magnetic field Looping a wire into a coil will create a combined magnetic field A solenoid is created when a current is passed through the looped wire A solenoid is created when a current is passed through the looped wire

10. Electromagnets An electromagnet is made when an iron core is placed inside the looped wire or solenoid An electromagnet is made when an iron core is placed inside the looped wire or solenoid Electromagnets are very strong magnets that can change strength & direction with a change in current Electromagnets are very strong magnets that can change strength & direction with a change in current

11. Electromagnets Increasing the current will increase the electromagnet’s strength Increasing the current will increase the electromagnet’s strength Increasing the amount of wire loops in the solenoid will also increase electromagnetic strength Increasing the amount of wire loops in the solenoid will also increase electromagnetic strength

12. Video (3:18) “Electromagnetism: Magnetic ForceVideo (3:18) “Electromagnetism: Magnetic Force” Video (3:18) “Electromagnetism: Magnetic Force

13. Electromagnetic Devices Electromagnetic devices include electric motors, galvanometers, loudspeakers and generators Electromagnetic devices include electric motors, galvanometers, loudspeakers and generators Electric motors use electromagnets to turn an axle Electric motors use electromagnets to turn an axle

14. Electric motors contain a central iron core that is wrapped by many loops of wire (solenoid) Electric motors contain a central iron core that is wrapped by many loops of wire (solenoid) As the current flows through the wires magnetic fields are created As the current flows through the wires magnetic fields are created The magnetic fields create a push & pull which forces the axle to turn The magnetic fields create a push & pull which forces the axle to turn Electromagnetic Devices

15. How an Electric Motor Works

16. A galvanometer uses an electromagnet to measure small amounts of current A galvanometer uses an electromagnet to measure small amounts of current Galvanometers are used to gauge how much gasoline is left in a car & for laser guidance systems Galvanometers are used to gauge how much gasoline is left in a car & for laser guidance systems Electromagnetic Devices

17. Loudspeakers use a solenoid wrapped around one pole of a permanent magnet Loudspeakers use a solenoid wrapped around one pole of a permanent magnet Sound is reproduced as the changing current produces a change in magnetic fields Sound is reproduced as the changing current produces a change in magnetic fields Electromagnetic Devices

18. The magnetic force moves the solenoid back & forth causing a thin membrane to vibrate The magnetic force moves the solenoid back & forth causing a thin membrane to vibrate These vibrations produce sound waves from the speaker which closely matches the original sound These vibrations produce sound waves from the speaker which closely matches the original sound Electromagnetic Devices

19. Generators (AC & DC) convert mechanical energy to electrical energy Generators (AC & DC) convert mechanical energy to electrical energy A rotating coil of wire (or solenoid) placed in a magnetic field will generate an electric charge A rotating coil of wire (or solenoid) placed in a magnetic field will generate an electric charge

20. Electromagnetic Devices The electric charges are induced into a wire which then creates an electric flow The electric charges are induced into a wire which then creates an electric flow Generators resemble electric motors but generate electricity instead of using it (the opposite of electric motors!) Generators resemble electric motors but generate electricity instead of using it (the opposite of electric motors!) Video (3:49) “World’s First Electric Generator” Video (3:49) “World’s First Electric Generator”

21. Class Activity List three devices (not mentioned in this lesson) that use electromagnetic forces List three devices (not mentioned in this lesson) that use electromagnetic forces Explain what each device does and how electricity & magnetism interact in the device Explain what each device does and how electricity & magnetism interact in the device