Question

The curve represents the distribution of potential along the straight line joining the two charges $Q_1$ and $Q_2$ (separated by a distance r) then which of the following statements are correct?
1. $|Q_1|>|Q_2|$
2.$Q_1$ is positive in nature
3. A and B are equilibrium points
4. C is apoint of unstable equilibrium

• A. 1 and 2
• B. 1, 2 and 3
• C. 1, 2 and 4
• D. 1, 2, 3 and 4

Answer 1

The correct option is C 1, 2 and 4

The potential due to a charge $q$ is given by: $\frac{kq}{r}$

Since the potential around $Q_1$ is positive, the charge is positive.

Since the potential around $Q_2$ is negative, the charge is negative.

The potential at point A is zero.

$⟹\frac{k{Q}_1}{r_1}+\frac{k{Q}_2}{r_2}=0$

Since $r_1>r_2,$

$\left|Q_1\right|>\left|Q_2\right|$

Since potential has a local maxima at point C, it is a point of unstable equilibrium.