A point charge of +2.9 μC is located at the origin of a coordinate system and a second point charge of −5.9 μC is at x = 1.0 m.At what point on the x axis is the electrical potential zero?
A) +0.73 m
B) +2.97 m
C) +0.33 m
D) +25.52 m
E) +0.67 m

Question

A point charge of +2.9 μC is located at the origin of a coordinate system and a second point charge of −5.9 μC is at x = 1.0 m.At what point on the x axis is the electrical potential zero?
A) +0.73 m
B) +2.97 m
C) +0.33 m
D) +25.52 m
E) ​+0.67 m

Quizplus · Accepted Answer

The electric potential due to two point charges at some distance from them is given by:
V = kq1/r1 + kq2/r2
where k is Coulomb's constant, q1 and q2 are the charges, and r1 and r2 are the distances from the charges. 
Since we want to find the point on the x-axis where the potential is zero, we set V = 0 and solve for x. 
Putting in the values given, we have:
k(2.9x10^-6)/r1 + k(-5.9x10^-6)/(1-r1) = 0
Simplifying, we get:
r1 = 0.33 m
Therefore, the answer is choice C.

A Point Charge of +2