A student rubs a glass rod with a piece of silk to charge it. He then touches it to a metal sphere hung from a string. Which statement correctly describes what
happens?
a) The metal sphere will be attracted to the glass rod after it is touched.
b) The metal sphere will be repelled by the glass rod after it is touched.
c) The metal sphere will have a negative charge after the glass rod touches it.
d) The metal sphere becomes neutral once the glass rod is removed.