Magnet Experiment: Are Two Magnets Twice as Strong as One?

Each magnet has two poles, the north pole and the south pole. The North Pole gets its name because it is the magnetic north pole of Earth, which is currently near Ellesmere Island in Northern Canada. This means that the north pole of all magnets on Earth point to this location, including the ones on your refrigerator and the magnets you will use in this experiment. The south pole of all magnets on Earth point to the South Pole in Antarctica. The magnetic poles of the Earth gradually move over time because of the flow of the Earth’s core, which contains a lot of iron.

The term “opposites attract” comes from the concept of magnetism: north-south magnetic interactions will attract each other, while north-north and south-south interactions will repel each other. When bringing a magnet near an object that contains a lot of iron, like a steel paperclip, the magnet can lift up the object. Magnetic fields can be combined to be stronger or weaker depending on how they are put together.

Problem:

Determine whether the strength of the magnetic field created by two magnets is twice the strength of the magnetic field created by one magnet.

Materials

• 2 or more identical magnets 
• Steel paper clip
• Stack of index cards, sticky notes, or paper
• Stack of felt or cloth squares
• Ruler

Procedure

1. Take of the magnets and place an index card in between the magnet and the paper clip. Does the magnetic force of the magnet hold up the paper clip through the card? Record the data and your observations in a chart like the one below.

2. Add another card between the magnet and the paper clip and record your observations.
3. Keep adding cards one at a time until the magnet cannot hold the paper clip.
4. Count how many cards are between the magnet and paperclip.
5. Use the ruler to measure the height of the index card stack.
6. Repeat the experiment using squares of felt or cloth. 
7. Repeat both parts of the experiment using 2 or more magnets stuck together. When you combine magnets, you will need to use a magnet that does not have any casing so that they will stick together. Does the material between the magnet and the paperclip matter? Is the height of the cloth stack different than the paper stack? Why? Is the magnetic force greater when there is more than one magnet?
8. Graph your results. Try making a bar graph with “Number of Magnets” on the x-axis and “Number of Index Cards” or other material on the y-axis. This will help you determine if two magnets are twice as strong.​

Results

While two magnets together are stronger than one magnet, two magnets will not be twice as strong as one.

Why?

Two magnets together will be slightly less than twice as strong as one magnet. When magnets are stuck entirely together (the south pole of one magnet is connected to the north pole of the other magnet) you can add the magnetic fields together. Because of this, the magnet on top will be one magnet-height’s distance farther away from the paper clip.