Question

Two positive point charges of unequal magnitude are placed at a certain distance apart . A samll positive test charge is placed at null point, then:

• A. Charge is in equilibrium.
• B. A test charge is in stable equilibrium
• C. The test charge is in neutral equilibrium
• D. The test charge is in unstable equilibrium

Answer 1

The correct option is D The test charge is in unstable equilibrium

Consider two positive charges $Q_1$ and $Q_2$ are placed at $A$ and $B$, d distance apart. A null point $P$ is formed where net electric feild due to the charge is $0$ and there test charge is placed. on displacing charge $q$. in either vertical or horizontal direction, there is a net force on it, which doesn't restore it to equilibrium. rather,the net force repels the charge away. so at P,charge q. is in unstable equilibrium.