Find the electric field of a square at a given point?

[awilliam_3]

Homework Statement

Two tiny objects with equal charges of 6.00uC are placed at the two lower corners of a square with sides of 0.580m.

When facing the square, Point A is the top left corner. Point B is in the top middle. Point C is dead center inside the square.

Find the electric field at Point A, the upper left corner.

Homework Equations

E = K [q1 / d^2]

The Attempt at a Solution

Calculated E1 & E2 using above formula and givens, then took the difference to determine the electric field in N/C.

 

[Doc Al]

Calculated E1 & E2 using above formula and givens, then took the difference to determine the electric field in N/C.

Why did you take the difference? Instead, add the field contribution from each charge, remembering that the field is a vector and must be added as such.

 

[tiny-tim]

welcome to pf!

hi awilliam_3! welcome to pf!

Calculated E1 & E2 using above formula and givens, then took the difference to determine the electric field in N/C.

(are the charges the same sign, or opposite sign? if they're opposite, then yes, you subtract)

you can't just add (or subtract) the magnitudes, you have to add (or subtract) the forces as vectors

 

[awilliam_3]

Why did you take the difference? Instead, add the field contribution from each charge, remembering that the field is a vector and must be added as such.

Ah, I see. Thank you.

 

[awilliam_3]

hi awilliam_3! welcome to pf!


(are the charges the same sign, or opposite sign? if they're opposite, then yes, you subtract)

you can't just add (or subtract) the magnitudes, you have to add (or subtract) the forces as vectors

They are indeed the same sign. Great tip, thank you!