3. An archaeon has 7.6 × 1016 protons and a net charge of 4.2 pC. a) How many fewer electrons are there than protons? b)If you paired them up, what fraction of the protons would have no electrons?

2. If 6 million electrons are removed from a glass rod, what is the charge on the glass rod in coulombs? 3. A 5 µC charge is placed 2 cm from a -70 µC charge. Find the force between the two charges.

1. Consider four 1 Coulomb charges, arranged in a square, 1m on a side. a) What is the energy of a 1 Coulomb charge in the centre of the square? b) For fun (for some definitions of fun) express this quantity in terms of the energy released by the explosion of a ton of TNT. (What this really tells us is that a Coulomb is large amount of charge.)