Three identical point charges Q are placed at the vertices of an equilateral triangle (length of each side = 2.0 m).If Q = 60 $\mu$C,what is the magnitude of the electrostatic force on any one of the charges?
A)25 N
B)19 N
C)14 N
D)22 N
E)16 N

Question

Quizplus · Accepted Answer

The magnitude of the electrostatic force between two charges Q, separated by a distance r, is given by Coulomb's law: 
F = kQ^2/r^2, 
where k is Coulomb's constant (9 x 10^9 N m^2/C^2).
In this case, each charge Q is equidistant from the other two charges, and the triangle is equilateral, so the distance between any two charges is 2 m. Thus, the magnitude of the electrostatic force on any one charge is 
F = kQ^2/(2^2) = (9 x 10^9 N m^2/C^2)(60 C)^2/(2 m)^2 = 14 N. 
Therefore, the best choice is C, with an explanation as shown above.

Three Identical Point Charges Q Are Placed at the Vertices μ\muμ

Three Identical Point Charges Q Are Placed at the Vertices $\mu$