Question

The magnitude of the electrostatic force between two point charges Q and q of the same sign is given by ​F(x)

​, where x is the distance between the charges and k is a physical constant​ (C stands for​ coulomb, the unit of​ charge; N stands for​ newton, the unit of​ force). Use this information to answer parts​ (a) through​ (c) below.

Answer 1

The electrostatic force between two charges Q1 and q is given by

where

ke is the Coulomb's constant

Q1 is the first charge

q is the second charge

r is the distance between the two charges

Re-arranging the formula, we have

and since we know the value of the force F, of the charge Q1 and the distance r between the two charges, we can calculate the value of q:

And since the force is attractive, the two charges must have opposite sign, so the charge q must have negative sign

Explanation:

And since the force is attractive, the two charges must have opposite sign, so the charge q must have negative sign.