How would you make an electromagnet? (a) wrap insulation around a magnetic material, and create an electromagnetic field around the magnet. (b) cover a magnet with insulation, and apply an alternating electrical current to the magnet. (c) cover a twisted ferromagnetic material with insulation, and apply a direct current to the coil. (d) wrap an insulated wire around a metal with ferromagnetic properties, and apply an electric current.

Sally turns on her cellular telephone to speak to her friend who is located thousands of miles away. which of the following best describes how such a telephone is able to transmit and receive information? a. the cellular telephone transmits, receives, and encodes information using only sound waves. b. the cellular telephone transmits, receives, and encodes information using only electromagnetic waves. c. the cellular telephone transmits information by electromagnetic waves to a receiver which then encodes them and produces sound. d. the cellular telephone transmits information by sound waves to a receiver which then encodes them and produces electromagnetic waves.