Magnetism

​Non-contact Force - Magnetism

​The train in this photo is called a maglev train. The word maglev stands for “magnetic levitation.” Magnets push the train upward so it hovers, or levitates, above the track without actually touching it. This eliminates most of the friction acting against the train when it moves. Other magnets pull the train forward along the track. Because of all the magnets, the train can go very fast. It can fly over the tracks at speeds up to 480 kilometers (300 miles) per hour! What are magnets and how do they exert such force? In this article, you’ll find out. 

​Non-contact Force - Magnetism

​Magnetic Poles

A magnet is an object that attracts certain materials such as iron. You’re probably familiar with common bar magnets, like the one shown in the Figure below. Like all magnets, this bar magnet has north and south magnetic poles. The red end of the magnet is the north pole and the blue end is the south pole. The poles are regions where the magnet is strongest. The poles are called north and south because they always line up with Earth’s north-south axis if the magnet is allowed to move freely. (Earth’s axis is the imaginary line around which the planet rotates.)

Multiple Choice

What do you suppose would happen if you cut the bar magnet pictured in the previous image along the line between the north and south poles?

• Each half will become a new magnet with a north and south pole.
• The two halves will repel each other as they are cut.
• One half will become a magnet with only a north pole.
• The magnet will lose its magnetic properties entirely.

​Non-contact Force - Magnetism

Magnetic Force and Magnetic Field

The force that a magnet exerts on certain materials, including other magnets, is called magnetic force. It is a non-contact force, i.e., force is exerted over a distance and includes forces of attraction and repulsion. North and south poles of two magnets attract each other, while two north poles or two south poles repel each other. A magnet can exert force over a distance because the magnet is surrounded by a magnetic field. In the Figure below, you can see the magnetic field surrounding a bar magnet. The pattern of the iron filings shows the lines of force that make up the magnetic field of the magnet. The concentration of iron filings near the poles indicates that these areas exert the strongest force. 

​When two magnets are brought close together, their magnetic fields interact. You can see how they interact in the Figure below. The lines of force of north and south poles attract each other whereas those of two north poles repel each other. 

​Non-contact Force - Magnetism

Watch the video below to learn more about how magnets work:

Multiple Choice

What is a magnet primarily composed of?

• Plastic

• Wood

• Metal

• Glass

Multiple Choice

Which ancient civilization discovered the force of magnetism?

• Romans

• Egyptians

• Greeks

• Mayans

Multiple Choice

What happens when you run a magnet along another metal object multiple times?

• It creates electricity

• It creates a new magnet

• It demagnetizes the metal

• It makes the metal heavier

​Non-contact Force - Magnetism

Summary

• A magnet is an object that attracts certain materials, such as iron. All magnets have north and south magnetic poles. The poles are regions where the magnet is strongest.

• The force that a magnet exerts is called magnetic force. The force is exerted over a distance and includes forces of attraction and repulsion. A magnet can exert force over a distance because the magnet is surrounded by a magnetic field.