Two Point Charges Net Electric Field

In summary, the net electrical field at points x=+4 and x=-4 can be calculated using the equation E=kq/r^2. The charge of -2.5 µC at the origin will make the E field larger at point x=+4, so it should be added instead of subtracted. After rounding to the correct number of significant figures, the net electrical field is 3.5*10^7 for both points.
  • #1
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Homework Statement



Two point charges lie on the x axis. A charge of -2.5 µC is at the origin, and a charge of +8.5 µC is at x = 10.0 cm.

What is the net electrical field at points x = +4 and at x = -4?

Homework Equations



E = kq/r^2

The Attempt at a Solution



For x = +4...

E= 9x10^9(8.5x10^-6)/.06^2 = 21250000
E= 9x10^9(-2.5x10^-6)/.04^2 = -14062500

Net E = 7187500 (which is wrong)

How do I solve this? Thanks.
 
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  • #2
use absolute values for charges and then add/subtract them up qualitatively.

the -2.5uC will make the E field LARGER at point x=+4 so you would add it instead of subtract.
 
  • #3
That didn't work.
 
  • #4
I'm pretty sure it should work. What's the correct answer for both positions?
 
  • #5
It doesn't give me the right answer until I submit the right answer. I entered 35312500 for x = +4 and it says that is incorrect. (I submit the answers online)
 
  • #6
the answer is 3.5*10^7 after sig figs.
 
  • #7
theRIAA said:
the answer is 3.5*10^7 after sig figs.

It says that is wrong too
 

Related to Two Point Charges Net Electric Field

What is a "Two Point Charges Net Electric Field"?

A "Two Point Charges Net Electric Field" refers to the combined electric field created by two point charges. It is the vector sum of the individual electric fields created by each charge.

How is the net electric field calculated for two point charges?

The net electric field is calculated using the principle of superposition, where the electric fields of the two charges are added together vectorially.

What factors affect the strength and direction of the net electric field?

The strength and direction of the net electric field are affected by the magnitude and distance of the two charges, as well as the relative positioning of the charges.

What is the equation for calculating the net electric field?

The equation for calculating the net electric field is E = (kQ/r^2) * (cosθ1 + cosθ2), where k is the Coulomb's constant, Q is the charge of each point charge, r is the distance between the two charges, and θ1 and θ2 are the angles between the line connecting the two charges and the x-axis.

How is the net electric field represented graphically?

The net electric field can be represented graphically using electric field lines, which show the direction and relative strength of the electric field at different points in space. The closer the lines are together, the stronger the electric field is at that point.

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