Is Brass Magnetic?

Brass is a mixture of zinc (Zn) and copper (Cu). Both of these elements are not magnetic. When we mix zinc and copper to form the alloy brass, we also end up with a non-magnetic compound. So, brass is not magnetic.

Like aluminum, copper, and zinc, brass does interact with moving magnets. In the video below a brass plate on a pendulum will move rapidly in the absence of a magnet. But as is passes by magnets it is slowed down considerably. You can see a wooden plate isn’t affected by the magnetic field.

So while brass isn’t magnetic, it can interact with magnetic fields. This happens because the movement of a magnet (or the brass could be moving instead) sets up an electrical current in the brass. This current has its own magnetic field which interacts with the magnet. The effect is best felt with strong neodymium magnets.

At home you can feel the interaction by moving a strong magnet over a piece of brass. If you don’t have brass aluminum foil behaves in a similar manner. Perhaps most impressive is dropping a magnet down a brass, copper or aluminum tube. The video below shows a magnet being dropped down a thick aluminum pipe.

The effect is called the Lenz Effect. The moving magnet causes small magnetic fields, called eddy currents, to form in the metal (brass, aluminum foil/tube ...). These eddy currents have their own magnetic field (all electrical currents do). This is what is interacting with the moving magnet.