Unit 8 Section 1: What is Magnetism and Magnetic Fields

​Science Root of the Day:

DO NOW: Write what you think the example words mean in your lab manual.

Extra Credit: Find three additional words that use this root and write them and their definition in your lab manual (6 Points Max)

Section 1: What is Magnetism?

The American Crocodile is a threatened species that has come into conflict with humans encroaching on their natural habitat.​ Attempts to move crocodiles to sanctuary locations have been difficult due to their ability to feel and detect the Earth's Magnetic field, which they use to navigate and return to locations. Biologists in Mexico have found that relocating the crocodile while it wears a magnetic helmet interferes with its ability to use the magnetic field, and stops them from returning to their original home

Word Cloud

In 1-2 words, what does the word magnet mean to you?

Lesson Objectives

• Identify and describe the Properties of Magnets

• Explain how magnetic poles interact

• Describe a magnetic field

• Describe the Earth's Magnetic Field

What is a Magnet?

• Magnet: Any material that attracts iron and materials that contain iron

  • Can vary in size

Discovering Magnets

• Magnets have been used throughout history, even when people did not understand how they worked

  • Ancient Greeks discovered a rock called magnetite, which could attract iron and repel other magnetite rocks

• Magnetism: the attraction or repulsion of magnetic Materials

  • Most Magnets show the same properties of Magnetite

What makes a Magnet a Magnet?

• Magnets do three things

  • Attract iron and materials that contain iron

  • Magnets can attract or repel other magnets

  • If allowed to swing freely, one end of the magnet will always point north

Multiple Choice

Would this object be magnetic

• Yes

• No

Multiple Choice

Which of the following is not a property of Magnets?

• One end always points north if allowed to move freely

• Can Attract other magnets

• Can Repel other magnets

• Can attract iron

• Repels Copper

Multiple Choice

Why are paper clips attracted to magnets?

• They contain silver.
• They contain aluminum
• They contain tin.
• They contain iron. 
• They are made of metal

What are Magnetic Poles?

• Each magnet has two ends, regardless of the size or shape of the magnet

• Magnetic Pole: The area of the magnet where the magnetic effect is the strongest

  • Two types of Poles exist, one at each end of the magnet

    • North Pole: Points North

    • South Pole: Points South

How do Magnets Interact?

• When two magnets come together, how they behave depends on how the poles are arranged

• If opposite poles are brought together, they will attract

• If the same poles are brought together, they repel each other

Magnetic Force

• Magnetic Force: the attraction or repulsion between magnetic poles

  • Can cause an object to move

  • Is affected by the distance between the magnets

• Can be used to make high-speed vehicles

Multiple Choice

Two South Magnetic Poles brought near each other

• repel each other

• attract each other

• cancel each other out

• magnetize each other

Multiple Choice

Two North Magnetic Poles brought near each other

• repel each other

• attract each other

• cancel each other out

• magnetize each other

Multiple Choice

A North Magnetic Pole brought near a south magnetic pole

• Nullifies the south pole

• Attracts the south pole

• Repels the south pole

• Magnetizes the south pole

Multiple Choice

What causes a maglev train to move?

• Magnetic levitation and switching of magnetic poles

• Gravity-based movement on tracks.
• Internal combustion engine driving wheels.
• Steam propulsion using water pressure.

​

What is a Magnetic Field?

• While the magnetic force is strongest at the poles of a magnet, it also exists in other areas of the magnet

• Magnetic Field: the area of magnetic force around a magnet

  • Allows magnets to interact without touching

  • Can be formed from a single magnet or multiple magnets

Magnetic Field Lines

• Magnetic Field Lines Map out the invisible Magnetic field around a magnet

  • They spread out from one pole, curve around, and return to the other pole

    • Form a complete Loop from pole to pole

  • Lines always leave from the North pole and return to the South

  • The closer the lines are, the stronger the magnetic field

Earth's Magnetic Field

• The Earth behaves just like a giant magnet, with a north and south magnetic pole

  • Causes a compass to always point North

• The core of the Earth contains large amounts of liquid iron in motion due to convection currents

  • These currents help create the magnetic field of the planet

Earth's Magnetic Poles

• Earth has a North Magnetic pole and a South Magnetic pole

• They are not the same as the geographical North and South Pole

  • Magnetic Declination: the angle found between the geographic poles of the Earth and the Magnetic Poles of the Earth

• The magnetic poles shift and move with the convection currents in the core

Multiple Choice

True or False: Magnets can interact without touching

• True

• False

Multiple Choice

Where is the force of a magnet the strongest?

• At both of the poles

• In the middle

• Far away from the magnet

• At the North Pole Only

• At the South Pole Only

Multiple Choice

True or False: Magnetic field lines always cross each other

• True

• False

Multiple Choice

Magnetic field lines that are drawn closer to each other show.....

• a decrease in polarity

• an increase in polarity

• a smaller magnetic force

• a greater magnetic force

Multiple Choice

True or False: Earth's Magnetic Poles are not located in the same place as the geographic poles

• True

• False

Open Ended

Suppose you have two magnets that do not have their poles labeled. How could you tell which sides of the magnet have the same pole and which ones have the opposite pole?

Open Ended

Which magnet in the picture shows the North Pole? How do you know?