Uniform line of charge and point charge

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Homework Help Overview

The problem involves calculating the electric field components at a specific point due to an infinite line charge and a point charge. The line charge has a uniform linear charge density and is positioned parallel to the y-axis, while the point charge is located at a different coordinate.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate the electric field contributions from both the line charge and the point charge using Gaussian surfaces and trigonometric functions. Some participants question the correctness of the calculations and the assumptions made regarding the contributions from the line charge.

Discussion Status

Participants are sharing numerical results and discussing potential errors in calculations, particularly regarding the use of radians versus degrees in trigonometric functions. There is an ongoing exploration of the results without a clear consensus on the final answers.

Contextual Notes

The original poster expresses uncertainty about the correctness of their answers and mentions checking units. There is a specific focus on ensuring that the calculations align with the expected format of kN/C.

noagname
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Homework Statement


An infinite line charge of uniform linear charge density lambda = -3.1 mu or micro CC/m lies parallel to the y-axis at x = -1 m. A point charge of 0.7 mu or micro CC is located at x = 2.5 m, y = 3.5 m. Find the x- and y-components of the electric field at x = 3.5 m, y = 3.0 m.

Homework Equations


flux = E*A = Q/ε
E = kQ/r^2

The Attempt at a Solution


X axis:
To find the electric field from the line only: gaussian cylinder, centered on the line and r = 4.5m.
E*2∏*4.5*L = λL/ε -> E1 = λ/(ε*9*∏) to the left

From the point:
E2 = K(.7*10^-6)/1.25*sin(63.43°) to the right

Ex = E2-E1 Right?

Y axis:
The line don't matter because it cancels itself out. right?
Ey = K(.7*10^-6)/1.25*cos(63.43°) Down

Both answers need to be in kN/C, I'm at a loss, do you guys have any ideas? I have tried many different answers and I've checked all of the units.
 
Last edited:
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Your work looks good to me. What did you get for your final answer?
 
What are your numerical results?

ehild
 
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Likes   Reactions: 1 person
Welp, I just found my mistake. Damn Radians!
 

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