(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The sum of two point charges is 6µC. They attract each other with a force of 0.9 N, when kept 40 cm apart in vacuum. Calculate the charges.

2. Relevant equations

3. The attempt at a solution

q_{1}+(-q_{2}) = 6x10^{-6}

q_{1}-q_{2}=6x10^{-6}.......I

q_{1}=6x10^{-6}+q_{2}

According to Coulomb's law

F=q_{1}q_{2}/4πε_{0}r^{2}

.9=(6x10^{-6}+q_{2})q_{2}/4πε_{0}(.4)^{2}

.9=(6x10^{-6}q_{2}+q_{2}^{2})x9x10^{9}/.16

.144/9x10^{9}=6x10^{-6}q_{2}+q2^{2}

144x10^{-3}x10^{-9}/9=6x10^{-6}q_{2}+q_{2}^{2}

q_{2}^{2}+6x10^{-6}q_{2-}16x10^{-12}=0

(q_{2}+8x10^{-6})(q_{2}-6x10^{-6})=0

q_{2=}-8µC or q_{2}=6µC

The answers given in the book are q_{1}= 8micro Coulomb and q_{2}= -2 microcoulomb

I don't understand how to get this answer because when q_{2}= 8 microcoulomb and substituting in equation I , i get q_{1}+8micro coulomb =6 micro coulomb so q_{1}should be -2 micro coulomb

Did i miss anything in the steps? Members, please help me .

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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# Homework Help: Coulomb's law and related problem

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