Popular science film about the history of the discovery of the magnetic field, the use of the properties of the electromagnetic field in industry, healthcare, and communication systems. The film includes staged footage of experiments with an electromagnet by the English scientist William Sturgey, who lived in the 19th century. There is an electric magnetic lift, a dynamo, an automatic telephone exchange, and a telegraph machine. An ophthalmologist performing an operation. The pioneer launches a radio-controlled model boat. Hydroelectric dam.