What could you do to increase the electric potential energy between two negatively charged particles by a factor of 16?

Can anybody me with this? ? (picture included.)

What is a carrier wave and how does it affect what you hear on the radio

Arigid tank is divided into two equal parts by a partition. one part of the tank contains 3 kg of compressed liquid water at 400 kpa and 60°c while the other part is evacuated. the partition is now removed, and the water expands to fill the entire tank. determine the entropy change of water during this process, if the final pressure in the tank is 40 kpa. use steam tables.