Net Force on Charges in Equilateral Triangle System

[neelakash]

Homework Statement

Three rigid rods are joined to form an equilateral triangle ABC of side 1m.Three particles carrying charge 1C are placed at the vertices.The whole system is in equilibrium in an inertial frame.What is the magnitude of the net force on each of the charges?

Homework Equations

The Attempt at a Solution

This may not be a simple question as it looks at first.In fact,it is an MCQ type question with four answers given from where we are to select the correct one.

The answer is zero.
Since the system is in equilibrium,the charges should also be in equilibrium too.
Hence,net force on each charge is to be zero.And that is the answer.

But what about the Coulomb's force and all that?They are there.And here we must assume external forces of equal magnitude acting over the charges in appropriate direction so that no net force acts on the system.

It should not be surprising to assume external forces if we recall the Earnshaw's theorem.

I think my logic is OK.

Please respond and let me know if I am correct.

 

[Jhero]

Your logic is correct. In an inertial frame, the net force on each charge must be zero in order for the system to be in equilibrium. This means that there must be external forces acting on the charges to balance out the Coulomb's force between them. This is in accordance with Earnshaw's theorem, which states that a system of point charges cannot be in stable equilibrium solely under the influence of electrostatic forces.

Therefore, the correct answer to the MCQ would be zero. I hope this helps. Let me know if you have any further questions.