Eddy current braking
“How can we apply the theory of eddy currents to transportation?”
What separates scientists and engineers is very simple, scientists discover new phenomena about the natural universe, while engineers take this knowledge and apply it to accomplish something useful. For example, scientists might discover that a specific current forms when conductors had a changing magnetic flux is applied to it, and name it something like eddy current. Now, how could an engineer take a phenomena like this and make it do something productive for humanity?
Well, let’s think about it like an engineer. We know that this current occurs because of an external magnetic field. Furthermore, we know that when current interacts with an external magnetic field, a perpendicular force is formed on the medium of the current. So let’s go further and think about we can do with this force. Well, a force can oppose motion, so how about we take this physical phenomena and apply it to an area that involves motion, namely transportation.
Let’s suppose that we have wheels made out of a conductive material, and that these wheels are moving at a certain RPM. If we take a magnet, and put the wheels in between both poles, then the constantly moving wheels will experience a constantly changing magnetic flux since parts of the conductor will always be moving into and out of the field. This will in turn generate an eddy current, which will produce a force that opposes the motion of the wheel, which in turn will cause it to slow down and brake. Engineers have termed this mechanism eddy current braking. Eddy current are so popular that they are used in many different cases, whether it be recreational gym equipment or high speed electric trains!