How Many Electrons are Needed to Create a Force of 10^-19 N Between Two Spheres?

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SUMMARY

The discussion centers on calculating the number of excess electrons required to create a repulsive force of 10^-19 N between two small spheres spaced 3 cm apart. The formula used is Coulomb's Law, F = k(q^2/r^2), where the calculated charge q was found to be 1 x 10^-16 C. The participant initially calculated that 625 electrons were needed, but the correct answer is 25 electrons, indicating a misunderstanding in the application of the charge-to-electron relationship.

PREREQUISITES
  • Coulomb's Law (F = k(q^2/r^2))
  • Understanding of electric charge and the elementary charge (e)
  • Basic algebra for solving equations
  • Concept of force between charged objects
NEXT STEPS
  • Review the derivation and application of Coulomb's Law
  • Study the concept of electric charge and the elementary charge (1.6 x 10^-19 C)
  • Practice problems involving forces between charged spheres
  • Explore the implications of charge quantization in electrostatics
USEFUL FOR

Students in physics, particularly those studying electrostatics, as well as educators looking for problem-solving techniques in force calculations between charged objects.

lionel messi.
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1. Homework Statement :
the excess(equal in number) of electrons that must be placed on each of two small spheres spaced 3 cm apart, with force of repulsion between the spheres to be 10^-19N, is...?


3. The Attempt at a Solution :
since,
f=kq^2/r^2.
ive calculated q from here which is 1x10^-16N..
then used,
q=ne..
from here n becomes 625 electrons. but answer in my book is 25 electrons.can someone point out my mistake?
 
Physics news on Phys.org
Your answer is correct, 25 electrons does not give 10^-19 N.
 

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