Net Electric Field Between Two Point Charges

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SUMMARY

The discussion centers on calculating the net electric field between two point charges, specifically q1 = 4.90×10-5 C and q2 = 2.45×10-4 C, separated by a distance of d = 0.10 m. The user attempts to compute the electric field E(-0.100) using the formula E(x<0) = -k [(Q1/x2) + (Q2/(d-x)2)], but encounters errors in their calculations. Key issues identified include confusion over the sign in the distance and a potential miscalculation of the charge value for q2. The correct approach requires careful attention to the signs and units in the equations.

PREREQUISITES
  • Understanding of Coulomb's Law and electric fields
  • Familiarity with the concept of point charges
  • Proficiency in algebraic manipulation of equations
  • Knowledge of the constants involved, such as the electrostatic constant k (approximately 8.99×109 N m2/C2)
NEXT STEPS
  • Review the derivation and application of Coulomb's Law
  • Practice calculating electric fields for multiple charge configurations
  • Learn about vector addition of electric fields from multiple sources
  • Explore the concept of electric field lines and their representation
USEFUL FOR

Students studying electromagnetism, physics educators, and anyone involved in solving problems related to electric fields and point charges.

Rachelbot12

Homework Statement



Two point charges q1 = 4.90×10-5 C and q2 = 2.45×10-4 C are separated by a distance d = 0.10 m. Compute their net electric field E (x) as a function of x for the following positive and negative values of x, taking E to be positive when the vector E points to the right and negative when E points to the left.What is E(-0.100)?

Homework Equations



I tried the following equations, but I couldn't get any to work for any of the values of x:
E(x<0)= -k [(Q1/x^2)+(Q2/(d-x)^2]
E(0<x<d)= k [(Q1/x^2)-(Q2/(d-x)^2]
E(d<x)= k [(Q1/x^2)+(Q2/(d-x)^2]

The Attempt at a Solution



E(-0.100)= -9e9 [(4.90e-5/-0.01)+(2.45e4/0.04)] = -1.1e7 N/C

This is being marked incorrect and I don't know what I'm doing wrong. I've attempted multiple times with no luck.
 
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Does the exercise mention the origin of the x-coordinate ? Your equations place Q1 at x = 0 at Q2 at x = d.

I expect that is OK. But then I don't understand the minus sign before the 0.01
and I also don't understand the 2.45e4 if the charge is 2.45e-4 Coulomb !?

One or more typing / calculator keying errors ?
 

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