Static on Moving Object Forms Magnetic Field (Jul, 1940)
Static on Moving Object Forms Magnetic Field
To the shaft of an electric motor, attach a disk of hard rubber, or an old phonograph record. Electrify the disk by rubbing it with a woolen cloth. Now start the motor. Place a small magnetic compass near the edge of the whirling disk, and the needle will be deflected, showing that it has been brought into a magnetic field. Such a field is set up not only by electric current passing through a wire, a familiar phenomenon, but also by charges of static electricity on a moving object. The faster the disk spins, the greater will be the magnetic effect. This curious phenomenon was first noted by Prof. Henry A. Rowland, noted American physicist.