Where is the point when the potential is zero?

AI Thread Summary
The discussion focuses on finding points along the line between two charges where the electric potential is zero. The initial attempt yielded a distance of 2.76 cm, but the user encountered issues with the computer's response indicating missing values. Clarification was provided that the potential equation should account for the absolute distances from both charges. The user later calculated a second potential point at 0.0403 m but faced further errors related to the sign and values in the denominator. The conversation emphasizes careful attention to the formula and the correct interpretation of distances in the context of electric potential.
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Homework Statement


A 2.96 uC and a -1.85 uC charge are placed 4.48 cm apart. At what points along the line joining them is the potential zero? Let V = 0 at r = infinity and enter the smaller distance first.


Homework Equations



V = k*q/r


The Attempt at a Solution



V(total) = 0 = kq1/x + kq2/(0.0448 - x)

x = q1*d/(q1 - q2)

x = 2.76*10^-2 m


Is there something that I'm missing? The computer says that I'm missing another value..

Thanks
 
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"r" means distance, not difference between coordinates in the formula for the potential. If q1 is placed in the origin and q2 is on the positive x-axis at d, You should have written your equation as q1/|x|+q2/|x-d|=0. There are three possibilities to discuss: x>d, (the point is on the right from q2) 0<x<d (the point is between q1 and q2) and x<0 (the point is on the left from q1).

ehild
 
I came with a second answer of 0.0403 m

x(2) = -q1d/(-q1-q2)

but the computer says I'm giving it the wrong answer. Is there something that I'm doing wrong?
 
x(2)=-2.96/(-2.96+1.85) *4.48. It is not 4.03 cm!

ehild
 
Thanks. I knew I'll mess something up with the denominator because of "-q2" and q2 = 1.85*10^-6 C.
 
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