We’ve all seen those little white tags on product boxes to prevent shoplifting, but did you know that they rely on magnets to work? 

How It Works

Inside of these white tags is two metal strips and a thin, small magnet with a weak magnetic force. They work as an anti-theft device, thanks to the property of magnetostriction. This property causes ferromagnetic materials to change shape when introduced to a magnetic field. (Ferromagnetism means the structure of the iron is formed by a permanent magnet or is attracted to them). In stores, there are sensors on the doorway that transmit and receive a weak magnetic field. When an active anti-theft tag (meaning it hasn’t been demagnetized) enters this zone, oscillation will occur, and the sensor will read the changes in the magnetic waves, causing an alarm to go off. When consumers check out, the cashier will demagnetize the anti-theft tag with a device containing a neodymium magnet. Because the tag is demagnetized, oscillation will not occur, and the alarm will not sound. Similarly, the tag can also be reactivated by magnetizing it with a neodymium magnet. You can see a great explanation and visual representation of anti-theft magnets and magnetostriction in this video by Applied Science. 

Improve Security With Apex Magnets

At Apex Magnets, we sell a variety of neodymium magnets that can be used to magnetize and demagnetize anti-theft devices. Note: The magnet dimensions and strength depend on the specific application, which is why custom magnets could be an ideal solution for anti-theft devices.  If you’re interested in learning more about how magnets play a role in security, such as how warehouses use magnets for security or how security systems work, be sure to follow along on the blog.