Two positive point charges q and 4q are at x = 0 and x = L, respectively, and free to move. A third charge is placed so that the entire three-charge system is in static equilibrium. What are the magnitude, sign, and x-coordinate of the third charge?

Short Answer

Expert verified

The magnitude, sign and x-coordinate of the third chargex=L3andQ=-4q9

Step by step solution

01

Content Introduction

Suppose take +neQat distance x from the origin. The equilbrium Q must be-ne.

02

Content Explanation

Force at 0.F=0

kqQx2+kQ4qL2=0Q=-4qL2x2

Now force at P

kqQx2+kQ4q(L-x)2=0(Lx-L)=2x=L3

Substitute the value of x

Q=-4qL2+L29Q=-4q9

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