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# Magnets and Magnetism

This lesson aligns with Next Generation Science Standards (NGSS) PS3.C

Introduction
As a child, all of us have played with magnets. We have always been curious about magnets. At some orientations, they pull each other towards themselves, and at some, they move away from each other. The force that works behind this behavior of magnets is known as a magnetic force. It can be attractive or repulsive depending on its orientation with other magnets. In this article, we will explore the concept of magnetism, what are magnets, properties of magnets and, types of magnets.

What is Magnetism?
Magnetism is a concept introduced in science to help us understand the interaction between moving charges. Magnetism is defined as a force that is exerted by magnets when they attract or repel each other. Like other forces such as gravitational force and electrostatic force, magnetic force is an interaction at a distance.

Magnets
More than 2,000 years ago, the Greeks found a mineral containing iron that attracted objects. The mineral was found in a part of Turkey called magnesia, which is why the Greeks named it magnetite. In this era, any material that attracts iron or iron-containing material is called a magnet.

Properties of Magnet
Magnets are the most common example of objects that exhibit magnetism. All magnets have certain properties. For instance, all magnets have two poles, affected by forces and surrounded by a magnetic field.

Magnetic Poles
The magnetic effects are not evenly distributed throughout the magnet. For instance, if you take a bar magnet and dip it into a box paper clip, you will observe that most of the paper clips stick to the ends of the bar. So, we can conclude that the magnetic effects are strongest near the ends of the bar magnets, these ends are known as the poles of magnet.

North and South
Let’s perform an experiment, attach a magnet to a string so that the magnet is free to rotate, and then one end of the magnet always ends up pointing to the north. The pole of a magnet that points to the north is called the north pole. The opposite end of the magnet points to the south and is therefore called the south pole of the magnet.

Magnetic poles always exhibit attractive or repulsive forces when brought close together. Like poles repel, while opposite poles attract each other. A magnet's poles always come in pair, there is no magnet with only a north pole or only a south pole.

Types of Magnets
Magnets can be categorized into two main types: temporary magnets and permanent magnets.

Temporary Magnets
Temporary magnets are formed from materials that are easy to magnetize but can lose their magnetization easily. Temporary magnets require an electric current to generate a magnetic field. For instance, soft iron that is not mixed with any other materials can be made into temporary magnets.

Permanent Magnets
Permanent magnets are difficult to magnetize but tend to retain their magnetic properties better. Strong permanent magnets are formed with alnico (AL ni KOH)—an alloy of aluminum, nickel, and cobalt.

Earth as a Magnet
If s magnet is allowed to rotate freely, then one end of every magnet points to the north. For centuries, travelers and explorers have relied on this to help them navigate.

One Giant Magnet
In 1600, an English physician named William Gilbert suggested that Earth itself is one giant magnet. In fact, Earth shows such behavior if it has a bar magnet running through its center. The poles of this imaginary magnet are located near the geographic poles of Earth.

A compass needle is a small magnet, and the tip that points to the north is actually the north pole of the needle. The reason is that, the point of a compass needle will be attracted to the south pole of a bar magnet.

The Core of Matter
Scientists believe that the magnetic field of Earth is generated by the movement of electric charges in the Earth’s core. The core of the earth is made mostly of iron and nickel. The inner core of the earth is solid because it is under such great pressure. However, in the outer core, the pressure is less and the metals are in a liquid state. As Earth rotates, the liquid in the core flows and causes electric charges to move, creating a magnetic field.

Summary
• Magnetism defines as a force that is exerted by magnets when they attract or repel each other.
• Magnets exhibit magnetism. Magnets possess two poles, namely, the north (N) and south (S) poles, which exhibit attractive or repulsive forces when brought close together.
• Magnets can be categorized into two main types: temporary magnets and permanent magnets.

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