Understanding the Electric Force Between Like Charges

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In summary, the question asks about the magnitude of the force needed to prevent two particles with like charges from moving. The answer is Coulomb's constant k. The electric force between like charges is repulsive, so without interference, the particles would move apart. To keep one particle from moving, an equal and opposite force must be applied.
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acherentia
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This is an ultra-simple question that I can't wrap my head around.

Two particles, both with charge +1C are located 1 m apart. If q1 is held in place, what is the magnitude of the force that must be exerted on q2 to keep it from moving?

The answer is Coulomb's constant k.

I don't understand why an electric force between two particles of like charge would keep the two charges in place. Or is this exactly what the electric force does? Shouldn't the two particles experience repulsion and move further from each other?

The way the question is asked it sounds as if the electric force is the force which at the value k prevents charges from moving. Doesn't that go against the fact that the electric force is either attractive or repulsive? What parameters would have to change in this problem for the charge to be repelled from one another?

I am sorry if this sounds confusing. I am really confused!
 
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  • #2
The two charges, being both positive, will repel. That is correct.
Left like that with no interference, they will both move off in opposite directions due to this mutual repulsion. The mutual force is given by Coulombs Law.
If you hold one of the charges so it can't move, there is still the same mutual repulsion, but while that one stays where it is, the other, free to move, will move away. To stop it moving away you would need to apply a force on it equal to that original repulsion force; but of course you would need to push the other way to counteract the repulsion. That is, push it towards the other charge.
 
  • #3
This makes perfect sense. Thank you.
 

FAQ: Understanding the Electric Force Between Like Charges

What is holding together two charges?

Holding together two charges refers to the force of attraction or repulsion between two electrically charged particles. This force, known as the Coulomb force, is responsible for keeping charged particles in close proximity to one another.

What factors determine the strength of this force?

The strength of the Coulomb force between two charges depends on the magnitude of the charges and the distance between them. The force increases as the magnitude of the charges increases and decreases as the distance between them increases.

What happens when two charges with the same polarity are held together?

When two charges with the same polarity (positive or negative) are held together, they will repel each other due to the Coulomb force. This means they will move away from each other, seeking to reach a state of equilibrium where the force between them is balanced.

How does the distance between two charges affect the force between them?

The force between two charges decreases as the distance between them increases. This is because the force follows an inverse square law, which means that as the distance between two charges doubles, the force between them decreases by a factor of four.

Can the force of attraction between two charges ever be greater than the force of repulsion?

No, the Coulomb force is always repulsive between two charges with the same polarity and attractive between two charges with opposite polarity. The strength of the force may vary depending on the magnitude and distance of the charges, but it will always follow this pattern.

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