Identify all of the following 4 charge distributions in which the electric field magnitude is equal to zero at the given point: 1) Any point above an infinite sheet of charge with uniform charge per unit area; 2) Inside a cylinder, when the cylinder is infinitely conducting with a radius R and charge per unit length lambda; 3) A point which is a distance R from an infinite wire, with charge per unit length lambda; 4) A point inside a conducting sphere of radius R, with charge q on the surface.