Question

A metal wrench is suspended from two thin, non-conducting wires. You have a glass rod that has been positively charged by rubbing it with a piece of (fake) fur. How might you use the rod to give a wrench a net negative charge?

Answer 1

Since the glass rod has already a positive charge and also the metal wrench is neutral, the metal wrench can be charged using the technique of charging by induction.

While bringing the positively charged glass rod near the metal wrench the electrons in the metal wrench got rearranged. As a result a negative charge will be accumulated near the surface in which glass rod is kept near. Then we can remove the glass rod to a larger distance. Thus the negative charge will get evenly distributed in the metal wrench. As a result a net negative charge is developed.