In our previous blog article we took a look at how a DC and an AC motor works and described how you can build your own basic DC motor. Even simpler than a basic DC motor, is a homopolar motor. First created in 1821, it really is the simplest example of a motor possible, and really easy to experiment with. What is a homopolar motor? We’ve already established that a homopolar motor is a type of electric motor, specifically it is one that uses direct current to power rotational movement, such as that generated by a battery. It was the first type ever built and demonstrated by Michael Faraday in 1821. Although not the configuration Faraday used, homopolar motors can be made out of a single AA or C battery, a single neodymium disc magnet and a piece of copper wire. They have two magnetic poles provided by the single permanent magnet that is used to produce the magnetic field, also required to generate rotational movement. It is called a homopolar motor because, unlike conventional DC motors, the polarity of the magnetic field emitted by the conductor and the permanent magnets does not change. Let’s take a close look at how one works. How does a homopolar motor work? OK, we’re going to get scientific for this bit so make yourself a cuppa and bring your concentration face! A homopolar motor creates rotational movement because of what is known as the Lorentz force. What’s happening is that electrical current is flowing from the positive terminal of the battery to the negative and into the magnet. This current then flows from the centre of the magnet to the edge where the wire connects, it travels up the wire back to the positive terminal of the battery and the circuit is complete. Simple. But how does this generate movement you may well ask? Well, the key is the direction of the current and the magnetic field produced by the permanent magnet. We’ve put together the below diagram to support the explanation. The direction of the magnetic field is demonstrated by the red arrows and the direction of current is shown by the blue arrows. As the current travels perpendicular to the magnetic field, a Lorentz Force is exerted on the on the conductor (the wire) which again is perpendicular to both the direction of the magnetic field and the current, generating the spinning motion.