Practice question

**Electrostatic force** described by F = (1/4π ε₀)·q₁q₂/r² obeys Newton's third law. Magnitude depends on q₁q₂ and 1/r², enabling quantitative estimation at given separation, with sign indicating attraction or repulsion. The electric field has a unique direction at each point, defined by the force on a test charge. Crossing lines would imply multiple directions at one point, which is impossible in a static field where the field vector is well-defined. Substituting values gives Unique direction, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's principles and charge quantization consistency.