If the charge is greater than zero (positive) then E field force goes out of reference point and if below zero (negative) then the E field force goes in to reference point Charge magnitude unless specified is 1.6E­19 C E = kq/r = mg/q F = Eq E field force only requires one charge to be present Positive charge field points to negative charge At point S, the distance is shorter to the electron and thus the will be affected more by this charge than the proton (pointing in to electron), while at point R it is closer to the electron so it will feel more of an affect from this charge. The proton field is also going toward the electron so either way the force field felt by point R will be to the left. Quiz review/explanations 1. positive charge goes to negative charge 2. field goes away from positive charges and since each point has the same charge then each point is mostly affected by the charge closest to it. 3. Equation for electric field shown above 4. Same charge and opposite position means that the charges cancel out resulting in zero 5. Due to symmetry, just as in four, the only way that all of the fields can cancel is if there is another charge present. 6. In position II or III the positive charge being added would be attracted to the negative charge near by, but in position I the positive charges will repel one another and the extra repulasion from the +2 charge will be canceled out by the attraction from the much farther away charge of ­4. 7. The sum of opposite fields results in the rightward vector 8. Since F = Eq