Consider a thin spherical shell centered on the proton, with radius r1 and infinitesimal thickness dr1. Since the shell is so thin, every point within the shell is at essentially the same radius from the proton. Hence the amount of electron charge within this shell is equal to the electron charge density rho(r1) at this radius multiplied by the volume dV of the shell. What is dV in terms of r1?

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.