The potential energy and electric field?

ELECTRIC POTENTIAL, POTENTIAL ENERGY & WORK DONE BY THE ELECTRIC FIELD. Urgent.....?

• Two point charges + 4.0x10^-9C and - 4.0x10-9C are placed on a straight line as shown in the Figure 1 below: +4.0x10^-9CA B - 4.0x10-9C -I-----------------I------I----------I… <---------------><--><---------> 20.0cm 10.0cm 10.0cm Find the total electric potential due to the two point charges at location A and B. (Ans: VA= 0V and VB= -240V)

• Answer:

  To find the total Electric potential at any point. You find the sum of all the electric potentials. Find the electric potential of A relative to the first charge, then find the electric potential of A relative to the second charge. Then its simple strait line vector addition, add the two values for your answer. V= kq/r where V equals voltage or electric potential (exact same thing), k equals a constant 9.0x10^9, q equals the charge of your point charge, and r equals the distance from the point charge. Va= (9.0x10^9)(-4.0x10-9)/ 20 = -1.8V Va= (9.0x10^9)(+4.0x10^-9)/ 20 = 1.8V Point A is equidistant from both charges. Since both charges of of equal magnitude and opposite charge the net electric potential is 0. That was the easy one now do the same process for point B. Find the electric potential relative to the two point charges and add the answers together. + - signs are the biggest errors with these type of questions.