The drawing shows a positive point charge +q1, a second point charge q2 that may be positive or negative, and a spot labeled p, all on the same straight line. the distance d between the two charges is the same as the distance between q1 and the spot p. with q2 present, the magnitude of the net electric field at p is twice what it is when q1 is present alone. given that q1 = +0.20 μc, determine the magnitude |q2| when q2 is

Materials will have different energies associated with the electrons inside them. this is related to how strongly bound they are by their work function. if we sandwich a material with a very low energy between two materials with a high energy, we create a trap for an electron. if this trap is very narrow in one direction in comparison to the others, this is approximately a 1-dimensional box that confines the electron. what is the lowest energy of an electron in the box if the thinnest direction across the materials is 4.81 nm?