
When copper wire is wrapped around an iron rod and connected to a battery, it becomes an electromagnet. A science teaching material movie that explains the principle and structure of electric bells and telephones by applying the principle of an electromagnet through a fusion of live action and animation.
Electrical Telegraphy, Electric Bells and Telephones was released in 1931.
Electrical Telegraphy, Electric Bells and Telephones has a runtime of 11min.
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