Lessons in practical electricity; principles, experiments, and arithmetical problems, an elementary text-book (1902)
Swoope, Coates Walton. [from old catalog] · New York, D. Van Nostrand company · leaf 204
=^^■■^^^4 … Fig. 174.—Magnetic Field of a Solenoid and Core.Made with iron filings on a hori-zontal piece of cardboard. 186 PRACTICAL ELECTRICITY. the iron bar, causing them to change the relation of theiiinternal magnetic circuits with respect to each other, thusproducing an external field near the ends of…
Electricity · Magnetism
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