Find the force on a charge `q_(1)(=20 mu C)` due to the charge of `q_(2)(=10 mu C)` if the positions of the charges are given as `P_(1)(1,-1,2)` and `Q(-1,1,1)`.
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Explanation

`vec(F_(12))=(q_(1)q_(2)vec(F_(12)))/(4 pi epsilon_(0)r_(12)^(3))`
where `vecr_(12)=vecr_(1)-vecr_(2)=(hat(i)-hat(j)+2hat(k))-(hat(i)+hat(j)=hat(k))`
`=2hat(i)-2hat(j)+hat(k)`
and `r_(12)=|vecF_(12)|sqrt(4+4+1)=3`
or, `vecF_(12)=((9xx10^(9))(20xx10^(-6))(-10xx10^(-6)))/((3)^(3)) (2hat(i)-2hat(j)+hat(k))`
`=-0.06(2hat(i)-2hat(j)+hat(k))N`.