1. The potential energy, E, of the interaction in the crystal CsCl depends on the distance, r, between Cs+and Clas E(r)=4ore2M+r9B where M=1.7,B=1.1910104Jm9 or 7.44105eV(nm)9,0=8.91012F/m a) (10 points) Sketch the potential energy as a function of r