Four equal charges q₀ each, are kept fixed on the vertices of a square of side 'a'. Charge q₁ is kept at the center of the square as shown in the figure. Then which statement is correct ? (Here charge q₁ is restricted to move perpendicular to XY plane i.e. along z-axis)

Question

G1 Physics · Accepted Answer

Step 1: Identify the relevant electrostatic principle—Coulomb's law, superposition, Gauss's law, potential-energy conservation or conductor boundary conditions. Step 2: Write the corresponding equation using the quantities in the question and simplify the geometry. Step 3: Substitute the given values and compare with the alternatives. Final: C: charge q₁ is always in stable equilibrium only if q₁ and q₀ have different (opposite) signs..