Question

Two point charges with charges $3$ micro coulombs and $4$ micro coulombs are separated by $2$ cm.The value of the force between them?

• A. $600N$
• B. $300N$
• C. $540N$
• D. $270N$
• E. $400N$

Answer 1

Answer: (D)

$270N$

Given : $Q_1=3\times {10}^{-6}C$ $Q_2=4\times {10}^{-6}C$ $r=2cm=0.02$ $m$

Coulomb force between them $F=\frac{K{Q}_1{Q}_2}{r^2}$ where $K=\frac{1}{4\pi {ϵ}_o}=9\times {10}^{9}N{m}^2{C}^{-2}$

$\therefore$ $F=\frac{9\times {10}^9\times (3\times {10}^{-6})\times (4\times {10}^{-6})}{(0.02{)}^2}=270$ $N$