Question

How will the electrostatic force between two electric charges change if the first charge is doubled and the second charge is only one third of the original charge?
A) 4/9
B) 2/3
C) 6 times
D) 2/9

Answer 1

Answer:

B) $\frac{2}{3}$

Explanation:

The electric force between charges can be determined by;

F = $\frac{kq_{1} q_{2} }{r^{2} }$

Where: F is the force, k is the Coulomb's constant, $q_{1}$ is the value of the first charge, $q_{2}$ is the value of the second charge, r is the distance between the centers of the charges.

Let the original charge be represented by q, so that;

$q_{1}$ = 2q

$q_{2}$ = $\frac{q}{3}$

So that,

F = $q_{1}$$q_{2}$ x $\frac{k}{r^{2} }$

  = 2q x $\frac{q}{3}$ x $\frac{k}{r^{2} }$

  = $\frac{2q^{2} }{3}$ x $\frac{k}{r^{2} }$

  = $\frac{2}{3}$ x $\frac{kq}{r^{2} }$

F = $\frac{2}{3}$ x $\frac{kq}{r^{2} }$

The electric force between the given charges would change by $\frac{2}{3}$.