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Fig. 48d. USEFUL MECHANICAL MOVEMENTS
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With the first principles of mechanics well in mind and the mechanical movements I have given, you can go on with your experiments in a safe and sensible way.
How to Experiment with Electricity.—Electricity is very much like mechanics in that any one can put up an electric bell or screw in a plug-fuse but to experiment and build an apparatus in which electricity and magnetism are the powers used you must know how electricity is generated, how magnetism is produced, the different forms of electricity that are available and finally the kinds of apparatus best suited for the work that is required of them.
Forms of Electricity.—Though there is only one kind of electricity it can be divided into four classes, or forms, and these are:
(1) Electricity at rest, or static electricity, that is electricity stored up but not active as in a charged Leyden jar.