MAGNETISM Grade 5 HOW ARE ELECTRICITY AND MAGNETISM

MAGNETISM Grade 5

HOW ARE ELECTRICITY AND MAGNETISM RELATED?

USES OF ELECTRICITY AND MAGNETISM: NATIONAL GEOGRAPHIC Video

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.

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

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?

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.

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

MAGNETISM AND OUR WORLD Magnets impact our lives in many ways…. Lets learn how!

MAGNETISM AND OUR WORLD Topics of investigation: 1) Earth’s Magnetic Field 2) Magnetic Compass 3) Magnetic levitation

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

2) EARTH’S MAGNETIC FIELD Surrounding this is the outer core � Made of: Iron, nickel, and smaller quantities of other metals � Size: 2, 000 km � Temperature: 3, 700°C � Pressure: lower pressure than the inner core � State of matter: fluid

2) EARTH’S MAGNETIC FIELD What is caused by the differences in temperature, pressure, and composition? ideas with a partner! What do we know about: Cool and dense matter? � Share � Sinks! Warm and less dense matter? � Rises! This creates convection currents!

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

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

2) MAGNETIC COMPASS What is a compass? No matter where on earth you stand, you can hold a compass in your hand it will point toward the North Pole

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

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

3) MAGNETIC LEVITATION Fastest to slowest: � Airplanes � Train � Cars � Boats � Buses � Bike � Feet Order these from most to least energy efficient

3) MAGNETIC LEVITATION Most energy efficient to least energy efficient � Bike � Foot � Train � Boats � Plane � Car � Bus

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

3) MAGNETIC LEVITATION Maglev is short for magnetic levitation These trains float over a track The principles of magnetism make this possible!

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

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

What cities currently have a Maglev train? ! HOMEWORK