A charge of 2.9 nC and a charge of 5.8 nC are separated by 40.80 cm. Find the equilibrium position for a -5.0 nC charge.

Hi Ace

Let A and B be the positon of 2.9 nC and 5.8 nC (A is on the left of B). Now put -5.0 nC on the left of A, between AB, and on the right of B. Draw electric forces acting on -5.0 nC at the three positions and find one that can make the resultant force on -5.0 nC becomes zero. Using the formula of electric force between two charges, find the position (distance from A or B)

Thanks, I tried it but i'm having no luck into fiding an accurate answer, Can i check mines? what did u get?

9.26 cm from A

EDIT : Actually I have another opinion but I just leave it for now. Can I know the answer from your manual?

Equilibrium position for a negative charge due to two positive charges can be obtained when the negative charge is placed on the line joining the two positive charges, inside the two charges and nearer to the smaller charge.If x is the distance of the negative charge form the smaller charge and d be the distance between the positive charges, the equilibrium position can be found by the equation
k*Q1/x^2 = k*Q2/(d - x)^2.
This position is independent of the magnitude of the negative charge.