Electric Potential -- work due to a non-conducting ring

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SUMMARY

The discussion centers on calculating the work done by an external force to move a point charge, q2 = -8.0 pC, from a position on the x-axis (x = 3.4 m) to the origin, influenced by a uniformly charged non-conducting ring with charge q1 = -9.8 nC and radius 1.2 m. The work is derived from the change in electric potential energy, expressed as W = ΔU = (q1q2)/(4πε) * (1/r - 1/√(r² + x²)). Here, r represents the radius of the ring, and x denotes the initial position of the point charge along the x-axis.

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  • Understanding of electric potential energy and work-energy principles.
  • Familiarity with Coulomb's law and electric fields.
  • Knowledge of the concept of electric potential due to continuous charge distributions.
  • Basic algebra and calculus for manipulating equations involving square roots and fractions.
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  • Study the derivation of electric potential energy from point charges and continuous charge distributions.
  • Learn about the application of Gauss's Law in electric field calculations.
  • Explore the concept of electric potential due to a ring of charge in greater detail.
  • Investigate the implications of moving charges in electric fields and the work done in such scenarios.
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Students and educators in physics, particularly those focusing on electromagnetism, as well as anyone involved in solving problems related to electric potential and work done by electric forces.

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Homework Statement


A charge of q1=-9.8 nC is uniformly distributed around a thin plastic ring lying in a yz plane with the ring center at the origin. A q2= -8.0 pC point charge is located on the x axis at x = 3.4 m. For a ring radius of 1.2 m, how much work must an external force do on the point charge to move it to the origin?

Homework Equations


U=W= (q1q2)/(4πεr)

The Attempt at a Solution


it says in the solution that W=ΔU= ( q1q2)/(4πε) * ( 1/r - 1/ √(r^2 + x^2) ) ; can someone please explain where did we get the ( 1/r - 1/ √(r^2 + x^2) ) from?
Thank you !
 
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You got it from the solutions...nyuck nyuck nyuck

What do r and x represent?
 

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