Question

A point charge $q_1=q$ is placed at point P. Another point charge $q_2=-q$ is placed at point Q. At some point $R(R\ne p,R\ne Q)$ electric potential due to $q_1$ is $V_1$ and electric potential due to $q_2$ is $V_2$. Which of the following is correct?

• A. Only for some points $V_1>V_2$,
• B. Only for some points $V_2>V_1$,
• C. For all points $V_1>V_2$
• D. For all points $V_2>V_1$

Answer 1

Answer: (C)

For all points $V_1>V_2$

Potential at R due to point charge at P, $V_1=\frac{k{q}_1}{x}=\frac{kq}{x}$
where x is distance between point P and R.
Potential at R due to point charge at Q, $V_2=\frac{k{q}_2}{y}=\frac{k(-q)}{y}$
where x is distance between point Q and R.
If the charge is positive, potential is positive and if the charge is negative, potential is negative. Hence option c is correct.