# Electrostatic Force

## Homework Statement

I have a question that I think I know, but it is kind of confusing me a little bit. The problem is as following:

Consider a charge of +3.2 C and a charge of -1.6 C separated by a distance of radius r. Which of the following statements correctly describes the magnitude of the electric force acting on the two charges?

a) The force on q1 has a magnitude that is twice that of the force on q2.
b) The force on q2 has a magnitude that is twice that of the force on q1.
c) The force on q1 has the same magnitude as that of the force on q2.
d) The force on q2 has a magnitude that is four times that of the force on q1.
f) The force on q1 has a magnitude that is four times that of the force on q2.

F = kq1q2/r^2

## The Attempt at a Solution

I think the answer is c, because no matter if you plug on kq1q2/r^2 or kq2q1/r^2, you'll get the same amount of force. Am I doing this correctly. I'm sure if I'm thinking of this problem in the right way. I know that q1 would emit a stronger electric weak, and q2 would have a weaker electric field, but I'm not sure how that relates to the amount of force q1 applies to q2, or q2 applies to q1. Is there a way to discriminate the force that q1 applies to q2, and q2 on q1?? Or are they the same?

PeroK
Homework Helper
Gold Member
2020 Award

## The Attempt at a Solution

I think the answer is c, because no matter if you plug on kq1q2/r^2 or kq2q1/r^2, you'll get the same amount of force. Am I doing this correctly. I'm sure if I'm thinking of this problem in the right way. I know that q1 would emit a stronger electric weak, and q2 would have a weaker electric field, but I'm not sure how that relates to the amount of force q1 applies to q2, or q2 applies to q1. Is there a way to discriminate the force that q1 applies to q2, and q2 on q1?? Or are they the same?

It is c). There's also a thing called Newton's third law to guide you!

It is c). There's also a thing called Newton's third law to guide you!

Thank you, that's makes a lot of sense. After reading a little bit, I understand newton's third law in an intuitive sense now.