Explanation:
Force between two charges is given by
[tex]F=k\frac{q_1q_2}{r^2}[/tex]
where q₁ and q₂ are charges and r is the distance between them.
Here one charge is doubled with keeping all others same.
q₁ = 2 q₁
We have
[tex]F_1=k\frac{q_1q_2}{r^2}\\\\F_2=k\frac{2q_1q_2}{r^2}\\\\\frac{F_1}{F_2}=\frac{k\frac{q_1q_2}{r^2}}{k\frac{2q_1q_2}{r^2}}\\\\\frac{F_1}{F_2}=\frac{1}{2}\\\\F_2=2F_1[/tex]
Magnitude of force doubles.
