You know how to calculate the force on a charge due to another charge, right? (Coulomb's Law) Now recall that force is a vector. So we need to find the vector sum of the forces on the electron due to the charges at points A and B.Originally Posted by Jones
Define midpoint of AB to be the origin (ie. I'm placing the origin at the electron.) I am going to define a positive direction to the right. (Point A is at -0.10 m and point B is at 0.10 m.) NOTE: I am taking the absolute value of the charges in the force formula and figuring out the direction of the force on the electron by whether the electron is attracted or repelled by the charge.
The force on the electron by the charge at A is:
(This force is in the negative direction since the two charges attract, indicated by the "-" sign out front.)
The force on the electron by the charge at B is:
(This force is in the negative direction since the two charges repel, indicated by the "-" sign out front.)
Now just add the two forces. Finally, to get the acceleration of the electron, use F = ma. I would describe the acceleration as being in the direction of A or B. (Ans. The acceleration is in the direction of point A.)
NOTE: In case you are using the "other" form of Coulomb's Law, use
The Coulomb constant, k is defined as .