Two charges $5 \times 10^{-8}$ C and $-3 \times 10^{-8}$ C are placed 16 cm apart on the x-axis (positive charge at the origin). On the line joining them, electric potential is zero at:

Set $V = k[q_1/x + q_2/d] = 0$ where $d$ is the distance from $q_2 = -3\times10^{-8}$. **Between the charges** (0 < x < 0.16): $5/x = 3/(0.16-x)$ ⇒ $x = 0.10$ m = 10 cm. **Beyond the negative charge** (x > 0.16): $5/x = 3/(x-0.16)$ ⇒ $x = 0.40$ m = 40 cm. Both points satisfy V = 0; no solution exists to the left of the origin (both terms have the same sign).