Consider the following system. The particle on the left has charge +Q and the pa
ID: 1586017 • Letter: C
Question
Consider the following system. The particle on the left has charge +Q and the particle on the right has charge -Q, and the two charges are separated by a distance 2r. If location A is halfway between the two particles, what is the potential V at position A? What would the force F be on a test charge q_0 located at position A? If the electric potential at a given point is zero, does it necessarily follow that the electric force on a positive charge is zero at that point? If the electric force on a positive charge at a given point is zero, does it necessarily follow that the electric potential is zero at that point?Explanation / Answer
a)
If we bring a charge Q from infinity and place it at point A the work done would be:
W=kq1/r1 +kq2/r2
r1=r2=r
W=KQ/r -kQ/r
=0
electric potential at point A=0
b)
F=Kq1q2/r2
k=constant=9*109
in this problem test charge is placed at point A
F=F1+F2
=K(Qq0/r2 _Qq0/r2)
=0
c)
The electric potential is a scalar quantity which quantifies the amount of electrical potential energy a unit test charge would have if it were placed at a specific point in space. ('Test charge' means that the charge is brought to that location without disturbing the other charges
In contrast, the electric field is a vector quantity (meaning it has both a magnitude and a direction). It quantifies the force a unit test charge would experience if it were placed at a specific point in space.
d)
If you have two point charges that are separated from each other, there is a point between them where the electric field is zero. The electric field of each is a vector quantity, and the two vectors cancel each other. The electric potential is a scalar quantity, and at the same point it is the sum of the two values.