1. Warm-up
What is a magnet?

2. Magnetism

3. What is Magnetism?
Magnetism is the force of attraction or repulsion of a magnetic material due to the arrangement of its atoms, particularly its electrons.
Moving charges create magnetic fields, so spinning electrons cause magnetism
Like poles will repel, opposite poles will attract

4. Non-magnetic Materials
In atoms containing many electrons, the electrons usually pair up with their spins opposite each other causing their fields to cancel each other.
Ex: wood & plastic

5. Ferromagnetic Materials
Materials where the electron spins do NOT cancel completely
Ex: Iron, Cobalt, Nickel
Atoms group together with similar electron spins. These groups are called Magnetic Domains.

6. An unmagnetized substance placed in a magnetic field, can become magnetized.
This happens when the spinning electrons of all domains line up in the same direction.

7. https://nationalmaglab
academy/watch-play/interactive/magnetic-domains

8. Magnetic Fields
The region where the magnetic forces act is called a “magnetic field”
Magnetic Field Lines describe the structure of magnetic fields in three dimensions.
Point away from N pole and toward S pole
The closer the lines are, the stronger the magnetic field

9. Magnetic Poles
The ends of a magnet are where the magnetic effect is the strongest
Each magnet has two poles – 1 north, 1 south.

10. Magnetic Forces
Like poles repel
Opposite poles attract

11. Poles of a magnet always come in pairs

12. How to break a magnet? Drop it Heat it Beat it
Put it in a different magnetic field
This causes the domains to become random again!

13. The Earth is a magnet The magnetic field is strongest near the
North and South
magnetic poles

14. Earth’s magnetic field helps us find direction
** Needle of a compass always points toward the magnetic South Pole.
We call this direction “North”

15. Current-Carrying Wire
A wire that has an electric current moving through it produces an electric field

16. Right Hand Rule
Find the directing of the magnetic field around a current-carrying wire
Point your right thumb in the direction of the current (I)
Your fingers point in the direction of the magnetic field (B) around the wire

17. Drawing Direction of a Magnetic Field

19. Solenoid
A solenoid is a coiled wire that acts as a magnet when carrying electric current.
Used in many home appliances and medical equipment

20. Electromagnet
The magnetic field of a solenoid can be increased by inserting an iron rod through the center of the coil. Creates a powerful, but temporary magnet.
Stronger Electromagnets
More coils
Higher voltage
Ferromagnetic core (IRON, steel, nickel, cobalt). Non-magnetic materials do NOT make good cores (wood, plastic, aluminum)

21. Warm-up What causes a magnetic field?
Moving charges create magnetic fields (spinning electrons)

23. Motor
A motor is a machine that uses electricity and magnets to convert electrical energy to mechanical energy.
Commutator- part of a motor that changes DC current to AC current to spin the magnet in the motor.
DC Current – current flows in one direction.

24. Generator
Machine that uses a magnetic field to produce electricity by spinning a wire coil in a magnetic field.
Uses wind, water, or steam
Mechanical to Electrical energy.
Produces alternating current.
Progress energy, home generators

25. AC Current AC-Alternating Current-Changes the direction it flows.
In US cycles 60 times /sec (Hertz)
Produces 120 Volts in outlets
Type from the power in our home
Needs a transformer to “step down” the voltage between the power plant and our home.

26. Superconductors
Elements that have no electrical resistance at temperatures near Absolute Zero.
Absolute Zero is 0 Kelvin or -273˚C
Critical Temperature is the temperature the substance becomes a superconductor.
Cool substances with liquid Helium (4 K)
Important because they are very efficient.
Do not lose energy (in the form of heat).

27. Meters
Ammeter – measures flow of electricity or current in amps. (connected in series)
Voltmeter – measures potential difference in volts (connected in parallel)
Galvanometer – meter that can be set to measure current or potential difference.