Three point charges are placed at the corner of an equilateral triangle. Assuming only electrostatic forces are acting.

Options

A. will be in equilibrium if the charges rotate about the centre of the triangle
B. can never be in equilibrium
C. will be in equilibrium if the charges have the same magnitudes but different signs
D. will be in equilibrium if the charges have different magnitude and different signs.

Answer

B

Explanation

Each charge will be acted upon by two forces due to two other charges placed at the two other corners of the equilateral triangle. Since the lines of action or the directions of those two forces are different irrespective of the magnitude and sign of the charges, the system can never be in equilibrium. one such case is shown in the figure, where `vecF_(R)=vecF_(12)+vecF_(13),vecF_(R)` is the resultant force on the charge `Q_(1)`.