Viewing Magnetic Fields and Identifying Magnetic Poles

By Shalea Hardison

Typically, magnetic fields are invisible.  It’s one of the things that adds to the mystique and curiosity of magnets.  Bust visualizing magnetic fields and identifying magnetic poles can be done with just a few simple tools.

Magnetic Fields

There are a few ways to detect magnetic fields, one of the most reliable is with magnetic viewer film. This unique film suspends tiny nickel particles over a thin layer of viscous material allowing the particles to align with magnetic fields. It shows the location, as well as how many poles, a magnet has. Simply place the sheet over the magnet and the poles appear as dark areas. The light green areas are the magnetic fields.

Magnetic viewer cards and sheets allow users to:

• Pinpoint location of magnetic poles
• Determine number of poles a magnet has
• Easily find ‘hidden’ magnetic fields

Make it Yourself

While viewer cards quickly illuminate poles, a simple DIY project illustrates magnet flux in motion. To make one, just a few simple items are needed.  Start by gathering the materials:

• a clear bottle
• mineral oil (or other viscous fluid like glycerin)
• iron filings
• assorted shapes of magnets

Carefully pour the oil into the bottle or container of your choice. Add coloring, if desired, and shake gently. Next add in iron filings. The amount added depends on the bottle size, but in order to see the iron particles moving, don’t add too much metal. At this point, all that is left is to cap the bottle and shake the contents. 

Rubbing a magnet along the outside of the bottle draws the metal filings along the magnetic field lines. Using different shapes of magnets fully illustrates magnetic flux.

A few tips:

• Use a viscous fluid like mineral oil or glycerin to suspend the iron filings. Water is not well suited for this use. 
• Iron filings, iron oxide or cut up pieces of steel wool all work to demonstrate the pull of the magnet. Easily purchase any of these supplies at local discount stores.

This project is excellent for demonstrating the magnetic field in motion and is ideal for educational purposes. Plus, it’s just plain fun!

Identifying Magnetic Poles

While magnetic viewer cards show the location of magnetic poles, they don’t classify the pole.  If determining a magnet’s north or south pole is important, then the tool to use is a pole finder.

This basic magnetic pole finder identifies the north or south pole of a magnet. An electronic version, beeps when then the pole is found and lights up red or green for pole indication.

Pole finders are very simple to use. Just touch the tip of the pole finder to the surface of the magnet and S or N appears in the window.

Pole finders are useful for:

• Verification of product assemblies
• Quality control
• Manufacturing applications
• Education

With science fair season in full swing, both magnetic viewing film and pole finders make useful tools for a variety of experiments. Master Magnetics offers several different types of magnetic viewing film and pole finders.  For more information about identifying magnetic fields, contact our Magnet Experts.