1. Permanent Magnet & Electromagnet Principles

2. Outline Permanent Magnets Electromagnets Poles Magnetic Fields
Characteristics of Fields
Uses
Electromagnets
How they are created
Magnetic fields

3. Permanent Magnets Holds a magnetic force Can not be turned on and off
Iron, Nickel, Cobalt and Gadolinium
Uses
Fridge Magnet
Speakers
Electric Motors
Many more….

4. Magnetic Poles
Refers to the ends of a permanent magnet, either North or South
Determined by its charge (placement of electrons)
Permanent Magnet S N

5. Magnetic field:
The region around a magnet or current-carrying body in which magnetic forces are observable
Permanent Magnet S N

6. Repelling Force Like Poles want to repel each other S N N S
Magnetic fields collide and push against each other

7. Attracting Force
Differing poles tend to be attracted to each other

9. Pith Balls

10. Metal Leaf Electroscope To detect current…

11. Electromagnets Use electricity to create a magnetic field
They can be controlled (turned on and off)
Their force or strength of field can be controlled

12. Electromagnet Basics Current-Carrying Wire Needs to have electron flow
Electromagnetic Field around a wire

13. Determining the Direction of the Magnetic field
Left-Hand Rule:
Grasp a wire with your left hand with your thumb pointing in the direction of current flow
Your fingers around the wire point in the direction of the field

14. Creating a Stronger Magnet
Coils
Each loop of coil has a small amount of magnetic pull
When the loops are added together the coil begins to act as a magnet with poles

15. Electromagnetic Field

16. Strength of Electromagnets
Depends on five foctors:
Number of turns/loops
Current through the coil
Permeability of the core material
Wire material type
Size/gauge of the wire

17. 1. Number of turns in the coil
The more turns in a coil, the stronger the magnet
The less turns the weaker the magnet

18. 2. Amount of current in the coil
- If the voltage is increased, so will the current,which will increase the strength of the magnetic field
- If the voltage is decreased the strength of the magnetic field will decrease.

19. 3. Permeability of the core material
- Permeability: The ability of a material to be magnetized, even temporarily, and to transmit magnetic force
- Air or glass would make a weak magnet
- Silver or iron would make a strong magnet

20. 4. Wire Material Type
Although, metal wires are very efficient conductors of electricity, they still have some resistance to the flow of current depending on the make of the metal.
Pure metals over alloys.
Silver, copper, gold., aluminum, zinc, nickel, brass, bronze are excellent conductors. Stronger magnets.
Mercury, lead, alloys of iron and chromium, titanium and stainless steel are poor conductors of . Weaker magnets

21. 5. Wire Size/Thickness/Gauge
Larger gauges of wire on the coil will decrease resistance. This will increase the current and therefore the field and the strength of the magnet.
Using smaller gauges will increase the resistance, reduce the current and weaken the field and weaken the magnet.

22. Putting Electromagnets to Use
Solenoid:
Is an electromagnet with a moveable core called a plunger

23. Uses for a Solenoid
Electrical Relays
Buzzers
Switches
Locks
Bells

24. Solenoid Uses

25. Other uses for Electromagnets
Transformers
Industry
Sensors
Motors

26. Summary
Magnets that hold their magnetic forces and can not be controlled are called__________.
Permanent Magnets
2. Refers to the region around a magnet or current carrying device where magnet forces are observed.
Magnetic Field

27. Summary (cont.)
3. How is the direction of a magnetic field determine around a current carrying wire?
Left-Hand Rule
4. What five things determine an electromagnet’s strength?
Number of turns/loops
Current through the coil
Permeability of the core material
Wire material type
Size/gauge of the wire