Hi, I found this on http://farside.ph.utexas.edu/teaching/302l/lectures/node32.html "Consider a charge placed in a uniform electric field (e.g., the field between two oppositely charged, parallel conducting plates). Suppose that we very slowly displace the charge by a vector displacement in a straight-line. How much work must we perform in order to achieve this? Well, the force we must exert on the charge is equal and opposite to the electrostatic force experienced by the charge (i.e., we must overcome the electrostatic force on the charge before we are free to move it around). The amount of work we would perform in displacing the charge is simply the product of the force we exert, and the displacement of the charge in the direction of this force." My question is why is the force we must exert on the charge is equal and opposite to the electrostatic force qE? Shouldn't the force be greater than qE? If it is equal and opposite than the charge won't move wouldn't it? Thank you.