Abstract
The ready availability of very strong permanent magnets in the form of rare-earth magnetic alloys such as neodymium-iron-boron has lead to renewed interest in one of the oldest types of electric motors - the homopolar motor. The ease with which a demonstration homopolar motor can now be built and operated when neodymium magnets are used is quite remarkable. In this paper some simple homopolar motors employing neodymium magnets suitable for demonstrational purposes are described and discussed.
Highlights
The importance and use of carefully selected demonstration experiments in the teaching of physics should not be underestimated
First invented in 1821 by the famous nineteenth century English scientist Michael Faraday (1791–1867), he built a type of electric motor which nowadays is referred to as a homopolar motor [3]
The aim of this paper is to describe and explain several of these recently proposed homopolar motors that teachers and lecturers of introductory-level physics may consider using to demonstrate the so-called motor
Summary
The importance and use of carefully selected demonstration experiments in the teaching of physics should not be underestimated. Demonstration experiments provide those we teach with an opportunity to gain and develop basic familiarity with a range of physically important phenomena [2]. Often it is those demonstrations performed with the simplest of equipment using arrangements and readily understood that are most likely to be long remembered. In contrast to most dc motors found today where commutators are used to reverse the direction of current flow in order to maintain continuous rotation, a homopolar motor is able to produce continuous rotation without the need for any such reversal in current It is the only known example of a true direct current motor and it is from its very means of operation the motor takes its name. An analysis of the dynamics of the roller is presented here for the first time
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