Understanding the Electric Force Between Like Charges

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SUMMARY

The discussion centers on the electric force between two like charges, specifically two particles each with a charge of +1C located 1 meter apart. The force required to keep one charge stationary while the other is free to move is equal to Coulomb's constant (k), which represents the mutual repulsion between the charges as described by Coulomb's Law. The confusion arises from the misunderstanding that the electric force itself can prevent movement, whereas it actually causes repulsion, necessitating an external force to maintain position. The key takeaway is that to counteract the repulsive force, an equal and opposite force must be applied to the moving charge.

PREREQUISITES
  • Coulomb's Law
  • Understanding of electric charge and forces
  • Basic principles of electrostatics
  • Familiarity with Coulomb's constant (k)
NEXT STEPS
  • Study the implications of Coulomb's Law in different charge configurations
  • Explore the concept of electric fields and their relation to charge movement
  • Investigate the role of external forces in electrostatic systems
  • Learn about the effects of varying charge magnitudes and distances on electric force
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Students of physics, educators explaining electrostatics, and anyone interested in the principles of electric forces and charge interactions.

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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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.
 
This makes perfect sense. Thank you.
 

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