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ziplock2k

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## Homework Statement

A point charge of +2.7 mC is located at the origin of a coordinate system and a second point charge of -7.8 mC is at x = 1.5 m. At what point on the x-axis is the electrical potential zero? Calculate to 2 decimal places.

## Homework Equations

## The Attempt at a Solution

net pot. diff will be zero at

x=1/3.

and at x = -1.

pot. diff is a scalar qty. so u can directly add it.

if the net potential diff at a pt (say at x,0) is zero,

we have

(k*3/x) - (k*6/(1-x)) = 0

2x=1-x

x=1/3

Similarly for negative x, u can make n eqn:

-(k*3/x) - (-k*6/(1+x)) = 0

which shal give u: x=-1

WHAT AM I DOING WRONG?