A-2.37 µc point charge and a 4.74 µc point charge are a distance l apart.
where should a third point charge be placed so that the electric force on that third charge is zero? (hint: solve this problem by first placing the -2.37 µc point charge at the origin and place the 4.74 µc point charge at x = −l.)

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.