Magnets and Magnetic Fields

Students continue to explore attractive and repulsive forces, focusing in this lesson on magnets. Students use iron filings to visualize the magnetic field interactions of permanent magnets and then test different-sized magnets.

• A magnet is any object that produces a magnetic field.
• A magnetic field is the area around a magnet that attracts or repels other magnets or magnetic materials such as iron.
• Stronger magnets have a larger magnetic field, and a magnet’s strength depends on its material. A magnet’s magnetic field is invisible, but other magnets within it will be pushed away from or pulled toward the magnet.
• All magnets have a north pole and a south pole. The north pole of one magnet always attracts the south pole of another. This is a pulling force.
• Two north poles will always repel each other. Two south poles will also repel each other. These are pushing forces.
  
  

• What happens to a magnet when it enters into another magnet’s magnetic field?
• How can we tell how large a magnet’s magnetic field is?
• What makes a magnet attract another magnet? What makes a magnet repel another magnet?
• What happens to non-magnetic objects that enter into a magnet’s magnetic field?
• Why do magnetic fields make magnets useful?
  
  

Misconception: All metals are attracted to magnets.

Fact: Not all metals are attracted to magnets. Iron, cobalt, and nickel are the three naturally occurring metals that are attracted to magnets.

Misconception: Larger magnets are always stronger than smaller magnets. 

Fact: A magnet’s strength depends on the materials that make it up. With two magnets of the same material, the larger magnet will be stronger than the small magnet. But in magnets made up of different materials, the smaller magnet may actually be stronger than the larger magnet.

Attract : to pull together

Repel : to push apart

Magnet : an object that produces a magnetic field; has a north and south pole; attracts or repels other magnets or magnetic materials such as iron

Magnetic Field : the area around a magnet that attracts or repels other magnets and magnetic materials such as iron

Permanent Magnet : an object that stays magnetized without electricity

Temporary Magnet : an object that acts like a permanent magnet when it is within a strong magnetic field

The World’s Strongest Magnet

The world’s strongest magnet is in Florida. It took 10 years to build this magnet. It is 6.7 meters (22 feet) tall.

Scientists from around the world come to Florida for the magnet. They carry out experiments that use the magnet. Most scientists stay for a week. Andreas Neubauer is a scientist from Germany. He stayed for six months.

Engineers have designed new types of materials with the help of the magnet. This is possible because matter acts differently inside a powerful magnetic field.

Magnets Have Magnetic Fields

A magnet is any object that produces a magnetic field. A magnetic field is the area around a magnet that attracts or repels other magnets or magnetic materials such as iron.

A magnetic field applies a force to other magnets or magnetic materials within it. This force can be a push or a pull.

All magnets have a north pole and a south pole. The north pole of one magnet always attracts the south pole of another. This is a pulling force.

However, two north poles will always repel each other. Two south poles will also repel each other. These are pushing forces.

Magnets are useful. They can attract or repel magnets or magnetic materials without touching them.

But objects are only affected by a magnet within its magnetic field. A magnet’s magnetic field is invisible. It moves from the magnet’s north pole to its south pole.

Stronger magnets have a larger magnetic field. A magnet’s strength depends on its material. There are different kinds of magnets depending on their properties.

Permanent magnets stay magnetized without electricity. Refrigerator magnets are permanent magnets.

Temporary magnets act like a permanent magnet when they are within a strong magnetic field. They lose their magnetism when the magnetic field goes away. Paperclips and iron nails are temporary magnets.

As the hands-on activity in this lesson, students use iron filings to visualize the magnetic field interactions of permanent magnets and then test magnets of different sizes. This lesson has two investigations. In the first investigation, students create visual models of the magnetic fields of attracting and repelling magnets. In the second investigation, students the relationship between the size of a magnet and its magnetic field. Students data on the magnetic fields and use this data they gathered in their investigations to construct an explanation about how magnetic forces act on different objects.