The net electric field at point A is 6.7x10^4Nm.

AI Thread Summary
The net electric field at point A is calculated to be 6.7 x 10^4 Nm, derived from the contributions of two negative charges. The electric field from charge 1 is vertical, contributing no x-component, while charge 2 is horizontal, contributing no y-component. The calculations involve using the formula Enet = k(q1/r^2 + q2/r^2), resulting in a total electric field of -6.0 x 10^4 Nm from the charges. It is emphasized that electric fields are vectors and should be added vectorially, leading to the final net electric field calculation. The discussion highlights the importance of considering components when charges are positioned along different axes.
chef99
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Homework Statement


Calculate the net electric field at point A.

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Homework Equations


Enet(total)

The Attempt at a Solution


[/B]
The electric field at point A will due to charge 2 will point towards charge 2 because charge 2 is negative.
The electric field at point A will due to charge 1 will point towards charge 1 because charge 1 is negative.

Enet(total) = Enetx + Enety
Because q1 is vertical, its x-component is 0. Because q2 is horizontal, its y-component is 0. Therefore,

Enet = kq1/r^2 + kq2/r^2

= (9.0x10^9Nm/C)(-6.0x10^-5C) / (3.0m)^2 + (9.0x10^9Nm/C)(-3.0x10^-5 C) / (3.0m)^2
= -60000Nm
= -6.0x10^4Nm
The electric field at point A due to the other charges is -6.0x10^4Nm


I am unsure if this is correct as this is the first time I've done a question when it hasn't been an equilateral triangle, so I don't know if I have the right idea or not. Also, I am unsure if I need to determine the angle of charge A or not. Any help is greatly appreciated.

**I am new to the forum so apologies for any errors in the format of my question.
 

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chef99 said:
Enet = kq1/r^2 + kq2/r^2

Do you know that Electric field is a vector, and so you have to add it vectorially?
 
PumpkinCougar95 said:
Do you know that Electric field is a vector, and so you have to add it vectorially?
I know the field is a vector, but do I still have to do the x- and y-components first if the direction of the two charges fall on the vertical and horizontal axis, as they appear in the diagram? i.e. Would the x-component for q1 not be zero?
 
Q1 will contribute no x component, Q2 will contribute no y component. But You have to Add them like $$ E_{net} ~=~\sqrt{ {E_x}^2+ {E_y}^2 } $$
 
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PumpkinCougar95 said:
Q1 will contribute no x component, Q2 will contribute no y component. But You have to Add them like $$ E_{net} ~=~\sqrt{ {E_x}^2+ {E_y}^2 } $$

So Enet = √60000Nm^2 + 30000Nm^2

Enet = 67082
Enet = 6.7 x10^4Nm
 
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