# Electrostatics: A square with point charges on the corners

• fara0815
In summary, the problem involves a system of movable point charges on the corners of a square. The fifth charge must be placed in the center and have a charge of -0.957q in order to achieve equilibrium. Using vectors and considering the four charges as one can help in solving the problem.
fara0815
Hello,
I am doing electrostatics at the moment and have difficulties to solve the following problem. Any hint that helps me to find the answer will be appreciated!

"On every corner of a square are movable point charges with the charge of 'q'. Where does a fifth movable point charge have to be and what charge does it need to have so that the system is in equilibrium?"

The answer is -0.957q and I do not know how to get that.

Well, "the system needs to be in equilibrium"...What equation do you use to express the equilibrium of the system ?

marlon

Mh, my idea is that you can consider the four charges as one since the electric field lines between them equal out, so that only the lines on the outside of the square act on a point charge.
The force caused by the four charges that acts on the fifth charge has to be a great as the force that is caused by the fifth charge and acts on the four charges.
Is that what you mean?

I figured it out!
I tried to do it without vectors and that just does not work ;)

If you do it with vectors and since it is symmetrical, you can calculate the forces acting on on point charge. The fifth point charge needs to be in the center.

## 1. What is electrostatics?

Electrostatics is a branch of physics that deals with the study of stationary electric charges and their interactions.

## 2. What is a square with point charges on the corners?

A square with point charges on the corners refers to a square-shaped object where electric charges are placed at each of the four corners. This can be used to demonstrate electric field and force interactions between the charges.

## 3. How does the distance between the point charges affect the electric field?

The electric field between point charges is inversely proportional to the square of the distance between them. This means that the closer the charges are, the stronger the electric field will be.

## 4. Can the charges on the corners of the square be of different magnitudes?

Yes, the charges on the corners of the square can be of different magnitudes. This will result in an uneven distribution of electric field lines and a net electric force acting on the charges.

## 5. What is the significance of using a square shape in this demonstration?

The square shape allows for a more symmetrical distribution of charges, making it easier to visualize and analyze the interactions between them. It also allows for a more controlled and predictable demonstration of electric field and force interactions.

• Introductory Physics Homework Help
Replies
21
Views
712
• Introductory Physics Homework Help
Replies
4
Views
842
• Introductory Physics Homework Help
Replies
17
Views
497
• Introductory Physics Homework Help
Replies
13
Views
675
• Introductory Physics Homework Help
Replies
24
Views
2K
• Introductory Physics Homework Help
Replies
1
Views
146
• Introductory Physics Homework Help
Replies
5
Views
730
• Introductory Physics Homework Help
Replies
12
Views
3K
• Introductory Physics Homework Help
Replies
11
Views
740
• Introductory Physics Homework Help
Replies
8
Views
771