Activity 27.1.1. Warm-up.
Write down something you know about magnets or magnetism, and how you know it. Where do you use magnets in your everyday life?
Section 27.1 What Is Magnetism?
Video Lesson 27.1.1. Magnetic Properties.
Magnets interact in many interesting ways with different types of materials. Key materials that exhibit prominent magnetic effects are permanent magnets and ferromagnetic materials.
Definition 27.1.2. Permanent magnets.
Permanent magnets are objects that have both attractive and repulsive interactions with each other. These objects have a “north” and a “south” pole that react to each other in different ways. Like poles repel and opposite poles attract.
Definition 27.1.3. Ferromagnetic materials.
Ferromagnetic materials (like iron, cobalt, and nickel) tend to be attracted to permanent magnets. Ferromagmetic materials can become permanent magnets through a process known as magnetization.
Video Lesson 27.1.4. A Model for Magnetism.
Subsubsection Key Ideas
Definition 27.1.5. Magnetic Field.
The magnetic field is a vector field that governs magnetic interactions.
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The magnetic field is a vector. Like other vectors, it has a magnitude and a direction. Magnetic fields are measured in units of tesla (T).
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The magnetic field has a value at every point in space. Either the magnitude or the direction (or both) can be different at different points in space.
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Magnetic fields can be observed with a compass. The north end of a compass needle will point in the direction of the magnetic field.
Subsubsection Activities
The experiments below will help answer some of the model questions posed in the video above.
Activity 27.1.2. Cutting a Magnet in Half.
Make a prediction about what you think happens if you cut a magnet in half. Then watch the following video in the answer to check your prediction.
Activity 27.1.3. Magnetic Grapes.
Make a prediction about what you think happens if you bring a magnet near a grape. Then watch the following video in the answer to check your prediction.
References References
[1]
“Magnetism: Cutting a magnet in half” YouTube, uploaded by QM Oxford, February, 18, 2019, https://www.youtube.com/watch?v=q0d_SS-0Puk&t=331s&ab_channel=QMOxford
[2]
“Magnetic grapes” YouTube, uploaded by Mark Lorch, March 24, 2012, https://www.youtube.com/watch?v=-zOzEvHmaK8
