M AGNETISM Grade 5

H OW ARE ELECTRICITY AND MAGNETISM RELATED ?

U SES OF E LECTRICITY AND M AGNETISM : N ATIONAL G EOGRAPHIC Video

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

E LECTROMAGNETIC FIELD What do you think happens to the electromagnetic field if the voltage is stronger? ElectromagnetsElectromagnets (click for hyperlink)

E LECTROMAGNETIC 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?

E LECTROMAGNETS 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.

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

M AGNETISM AND OUR W ORLD Magnets impact our lives in many ways…. Lets learn how!

M AGNETISM AND O UR W ORLD 1) Earth’s Magnetic Field 2) Magnetic Compass 3) Magnetic levitation Topics of investigation:

1) E ARTH ’ S M AGNETIC F IELD 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

2) E ARTH ’ S M AGNETIC F IELD 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

2) E ARTH ’ S M AGNETIC F IELD 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!

2) E ARTH ’ S M AGNETIC F IELD 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

2) E ARTH ’ S M AGNETIC F IELD 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

2) M AGNETIC C OMPASS 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

2) M AGNETIC C OMPASS 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

3) M AGNETIC L EVITATION How many forms of transportation can you think of? Airplanes Feet Cars Buses Bike Boats Train Order these from fastest to slowest

3) M AGNETIC L EVITATION Fastest to slowest: Airplanes Train Cars Boats Buses Bike Feet Order these from most to least energy efficient

3) M AGNETIC L EVITATION Most energy efficient to least energy efficient Bike Foot Train Boats Plane Car Bus

3) M AGNETIC L EVITATION What mode of transport is fastest and most efficient? Train!! Electromagnets are being used to develop high-speed trains These are called maglev trains

3) M AGNETIC L EVITATION Maglev is short for magnetic levitation These trains float over a track The principles of magnetism make this possible!

3) M AGNETIC L EVITATION 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

3) M AGNETIC L EVITATION 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

H OMEWORK What cities currently have aMaglev train?!