Multiplying by unit vector in electric field equation

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SUMMARY

The discussion focuses on calculating the electric field and force on a proton due to two point charges, specifically a 5.0 μC charge and a -4.0 μC charge, located at specified coordinates. The electric field equation used is E = (kq/r²) x [r-hat], where [r-hat] represents the unit vector in the direction of the electric field. Participants clarify that to find the electric field at point P (-3.0 m, 1.0 m), one must calculate the distances from point P to both charges, determine the angles, and resolve the electric fields into their horizontal and vertical components.

PREREQUISITES
  • Understanding of electric field equations, specifically E = (kq/r²).
  • Knowledge of unit vectors and their representation in Cartesian coordinates.
  • Ability to calculate distances and angles in a two-dimensional plane.
  • Familiarity with vector resolution into components.
NEXT STEPS
  • Study the concept of unit vectors in detail, focusing on their application in electric field calculations.
  • Learn how to apply the principle of superposition in electric fields from multiple point charges.
  • Explore vector resolution techniques, particularly in two-dimensional coordinate systems.
  • Practice problems involving electric fields and forces on charged particles in various configurations.
USEFUL FOR

Students in physics, particularly those studying electromagnetism, as well as educators and anyone involved in solving problems related to electric fields and forces on charges.

ChrisBaker8
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Homework Statement



A 5.0 μC point charge is located at x = 1.0 m, y = 3.0 m, and a −4.0 μC point charge is located
at x = 2.0 m, y = −2.0 m.

a) Find the magnitude and direction of the electric field at x = −3.0 m, y = 1.0 m. [5 Marks]
b) Find the magnitude and direction of the force on a proton at this position in a).

Homework Equations



E = (kq/r²) x [r-hat] (couldn't find the symbol for r circumflex)

The Attempt at a Solution



I can work out the first part of the equation, but I'm unsure what r-hat represents and what figure to use. I thought a unit vector was in the form Ai + Bj + Ck, how do you multiply that by a figure to get another single figure?
 
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Let point A be ( 1 m, 3 m) and point B be (2 m, -2 m). Let P be the point (-3 m, 1 m) where you want to find the electric field.
First of all find the distances AP and BP. Finding slope of the line AP and BP, you an find the angle made by the electric fields with x-axis. Then resolve them along vertical and horizontal components. Then find ΣEx and ΣEy and E.
 

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