1. Magnetism
Grade 5

2. How are electricity and magnetism related?

3. Uses of Electricity and Magnetism: National Geographic
Video

4. Electromagnetic field
Electromagnetic fields are everywhere around us.
An electromagnetic field is an invisible magnetic force that exists around any conductor that is carrying electricity.

5. Electromagnetic field
What do you think happens to the electromagnetic field if the voltage is stronger?
Electromagnets (click for hyperlink)

6. Electromagnetic field
Magnetism is “mediated” by the magnetic field
An electric current creates a magnetic field, and that field impacts magnetic forces on other particles that are in the field
In the picture above, the force of the bar magnet is shown by irons fillings on a piece of paper.
If we used a stronger magnet, what would happen to the iron fillings?

7. Electromagnets
Electromagnetism is created in a metal by the flow of electrons through a coil of wire wrapped around the metal.
The moving electrons emit a field that causes the electrons in the metal to “line up.”
This creates a temporary magnet.
As soon as the current stops flowing, the magnetic effect is removed.

8. Electromagnets Electromagnets are found in:
power door locks on vehicles
computers
electric motors
coils that produce the picture in television tubes
cell phones

9. Magnetism and our World
Magnets impact our lives in many ways…. Lets learn how!

10. Magnetism and Our World
Topics of investigation:
1) Earth’s Magnetic Field
2) Magnetic Compass
3) Magnetic levitation

11. 1) Earth’s Magnetic Field
Our planets magnetic field is generated deep in the Earth’s core
At the center of the Earth is a solid inner core
Made of: Iron
Size: almost as large as the moon
Temperature: 5,700°C
Pressure: very high due to force of gravity
State of matter: solid

12. 2) Earth’s Magnetic Field
Surrounding this is the outer core
Made of: Iron, nickel, and smaller quantities of other metals
Size: 2,000km
Temperature: 3,700°C
Pressure: lower pressure than the inner core
State of matter: fluid

13. 2) Earth’s Magnetic Field
What is caused by the differences in temperature, pressure, and composition?
Share ideas with a partner!
What do we know about:
Cool and dense matter?
Sinks!
Warm and less dense matter?
Rises!
This creates convection currents!

14. 2) Earth’s Magnetic Field
Convection Currents are caused because of the differences of temperature, materials, and pressure of the inner and outer core
This flow of liquid iron generates electric currents, which produces magnetic fields

15. 2) Earth’s Magnetic Field
Charged metals pass by each other which creates electrical currents of their own
The cycle then continues
This self-sustaining loop is known as the geodynamo

16. 2) Magnetic Compass What is a compass?
No matter where on earth you stand, you can hold a compass in your hand and it will point toward the North Pole

17. 2) Magnetic Compass How does a compass work?
Think of the Earth has having a gigantic magnet buried inside
The South end of the magnet is buried at the North Pole
Using the “opposites attract” rule, this causes the north end of the compass needle to point up

18. 3) Magnetic Levitation
How many forms of transportation can you think of?
Airplanes
Feet
Cars
Buses
Bike
Boats
Train
Order these from fastest to slowest

19. 3) Magnetic Levitation Fastest to slowest:
Airplanes
Train
Cars
Boats
Buses
Bike
Feet
Order these from most to least energy efficient

20. 3) Magnetic Levitation Most energy efficient to least energy efficient
Bike
Foot
Train
Boats
Plane
Car
Bus

21. 3) Magnetic Levitation
What mode of transport is fastest and most efficient?
Train!!
Electromagnets are being used to develop high-speed trains
These are called maglev trains

22. 3) Magnetic Levitation Maglev is short for magnetic levitation
These trains float over a track
The principles of magnetism make this possible!

23. 3) Magnetic Levitation There are three components to this system:
A large electrical power source
Metal coils lining a track
Large magnets attached to the underside of the train

24. 3) Magnetic Levitation How it works:
The large magnets repel each other
This allows the train to levitate 1 to 10 cm
Then power is supplied to the coils in the track walls
This creates a magnetic field that pulls and pushes the train
The magnetic field in front of the train pulls it forward
The magnetic field behind pushes it forward

25. What cities currently have a Maglev train?!
Homework