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# Net electric field from multiple charges in 2D

In this video David solves an example 2D electric field problem to find the net electric field at a point above two charges. Created by David SantoPietro.

## Want to join the conversation?

• An example without symmetry would be amazing. Would we just use the vectors to determine the direction and magnitude?
• It would be like how we sound the horizontal component in the example, but we would also use the method to find the vertical componant
• at , david solved this example taking into account the angle between the electric field and its x-component, isn't there any alternative to solve this problem other than finding the angles and then solving it?
• The alternative way is looking at the original triangle and observing that the horizontal component is 3/5 of the hypotenuse. So the electric field in the horizontal direction is 3/5 of the original electric field (2.88 N/C in our case).
(3/5)x(2.88 N/C)=1.728 N/C
Dave rounded that off to 1.73 N/C
• Are the words charge density and charge distribution refers to the same thing ?
• At , If we did have a vertical component...how do we get the final value i.e how do you apply the pythagorean formula?
• Just as in pytagorean theoren we have h=√(x^2+y^2) we can plug Ex(net) and Ey(net) in there place
Here you have to be careful about Ex(net) and Ey(net) they are the resolved components that is Ey(net)=Ey(from 1st charge)±Ey(from 2nd charge).The sign will depend on directon.If you only have one charge then Ey(net)=Ey(of the charge). In the video Ey=(sin58.1)2.88=2.30N/C but it will get cancelled out by other charge
• Do negative charges always have their vectors pointing towards them, and vice versa?
• Yes, electric field "points" away from a positive charge and toward a negative charge.
• if the negative charge was not -8.0 C. Let's say it is -10.0C
Would the y-components cancel out?
• of course not, it would be -2 net downards so then you would have to go through the same process as the E_X but for E_Y which is a substraction since oposite directions, you would then have to use sin to solve for those components rather than cos for the X
• DUDE. This is the first subject that is actually AWESOME. If I could learn this in school, I would wake up EVERY DAY excited to go to school.
• how did david got the horizontal and vertical component at ?
(1 vote)
• By resolving the two electric field vectors into horizontal and vertical components.
here is a Khan academy article that will you understand how to break a vector into two perpendicular components:

https://tinyurl.com/zo4fgwe

this article uses the example of velocity but the concept is the same. You can also search online for more tutorials on the resolution of vectors into horizontal and vertical components.