I've tried all three of these problems I dont know how mant times, and my work is just not correct. Any clue? The third prob, i really used some awkward equations. A particle has a charge of +1.53 mC and moves from point A to point B, a distance of 0.197 m. The particle experiences a constant electric force, and its motion is along the line of action of the force. The difference between the particle's electric potential energy at A and B is EPEA-EPEB=+9.39×10-4 J. Find (a) the magnitude of the electric force that acts on the particle and (b) the magnitude of the electric field that the particle experiences. The inner and outer surfaces of a cell membrane carry a negative and positive charge, respectively. Because of these charges, a potential difference of about 0.0680 V exists across the membrane. The thickness of the membrane is 7.95×10-9 m. What is the magnitude of the electric field in the membrane? Two hollow metal spheres are concentric with each other. The inner sphere has a radius of 0.1440 m and a potential of 86.0 V. The radius of the outer sphere is 0.146 m and its potential is 82.0 V. If the region between the spheres is filled with Teflon, find the electric energy contained in this space.