# Electrostatic Force - Locations of a second charge

Sandro Romualdez

## Homework Statement

A force of 2.4N [L] is exerted on a -1.8x10-6C charge 0.2m away. What are the possible charges and locations of the second charge?

FE= kq1q2 / d2

## The Attempt at a Solution

Rearranging the equation above for q2 is
q2 = FE x d2 / kq1

and substituting values gives an answer of
-5.9x10-6C.

Therefore, I have the charge value, but how do I know the locations of the second charge? Would it just be [Left or Right] of the 1st charge?

## Answers and Replies

Related Introductory Physics Homework Help News on Phys.org
TSny
Homework Helper
Gold Member

## Homework Statement

A force of 2.4N [L] is exerted on a -1.8x10-6C charge 0.2m away. What are the possible charges and locations of the second charge?
So the "[L]" for the force means toward the left?

and substituting values gives an answer of
-5.9x10-6C.
Does the charge have to be negative? Could a positive charge do the trick?

Therefore, I have the charge value, but how do I know the locations of the second charge? Would it just be [Left or Right] of the 1st charge?
Like charges repel and unlike charges attract. Think of the possibilities that would produce a force to the left on the given charge.

Sandro Romualdez
So the "[L]" for the force means toward the left?

Does the charge have to be negative? Could a positive charge do the trick?

Like charges repel and unlike charges attract. Think of the possibilities that would produce a force to the left on the given charge.
Yes, the [L] means the force is pushing the charge to the left. Since the charge calculated is -5.9x10-6 that would mean it is located to the left of the charge, since they are both negative and repel.

Sandro Romualdez
Yes, the [L] means the force is pushing the charge to the left. Since the charge calculated is -5.9x10-6 that would mean it is located to the left of the charge, since they are both negative and repel.
Also, the charge can be negative or positive, and if positive located to the right of the 1st charge, right?

TSny
Homework Helper
Gold Member
I think you have it. But to make sure, let q1 = -1.8x10-6 C.

If q2 = +5.9x10-6 C, then where is q2 located? Is it to the right or to the left of q1?

If q2 = -5.9x10-6 C, then where is q2 located? Is it to the right or to the left of q1?

Sandro Romualdez
I think you have it. But to make sure, let q1 = -1.8x10-6 C.

If q2 = +5.9x10-6 C, then where is q2 located? Is it to the right or to the left of q1?

If q2 = -5.9x10-6 C, then where is q2 located? Is it to the right or to the left of q1?
If it is positive, then it is to the left of q1 as it will attract and pull q1 towards it.

If it is negative, it is to the right, as it will repel and move the 1st charge away from it.

TSny
Homework Helper
Gold Member
If it is positive, then it is to the left of q1 as it will attract and pull q1 towards it.

If it is negative, it is to the right, as it will repel and move the 1st charge away from it.
Good.