Which two characteristics make electromagnetic waves effective in communication?
A. They do not require a medium to carry information.
B. They move faster through matter than through space.
C. They carry more energy than visible light.
D. They carry information very quickly.

(a) calculate the number of electrons in a small, electrically neutral silver pin that has a mass of 10.0 g. silver has 47 electrons per atom, and its molar mass is 107.87 g/mol. (b) imagine adding electrons to the pin until the negative charge has the very large value 1.00 mc. how many electrons are added for every 109 electrons already present