21. When an electrical conductor moves through a magnetic field, an electric current is induced into the conductor. 22. When radio waves pass an electrical conductor , the oscillating fields induce an alternating current in the conductor. 23. Copper is one of nature s most efficient thermal and electrical conductors , which helps to conserve energy. 24. The same thing also happens when the electrical conductor is stationary and the magnetic field is moving. 25. The phosphors are usually poor electrical conductors . 26. For example, saltwater is an electrical conductor . 27. In these cables, the optical fibers carry information, and the electrical conductors are used to transmit power. 28. The invention of the telephone in 1876 created further demand for copper wire as an electrical conductor . 29. Despite competition from other materials, copper remains the preferred electrical conductor in nearly all categories of electrical wiring. 30. Plastics can be good electrical conductors .
