Final answer:
The net potential at the empty corner of the square remains positive because the contributions from the two positive charges outweigh the contribution from the single negative charge since electric potential is a scalar quantity and can be directly added.
Step-by-step explanation:
The student question asks why the potential at the empty corner of a square with three-point charges is always positive, even if the charges are arranged in different ways with two positive charges and one negative charge. The explanation is based on the principles of electric potential and how it is calculated for point charges.
Electric potential (V) due to a point charge is given by V = kQ/r, where k is Coulomb's constant, Q is the magnitude of the charge, and r is the distance from the charge.
Since potential due to a positive charge is positive and due to a negative charge is negative, the net potential at a point is the algebraic sum of the potentials due to the individual charges. In this scenario, the net potential will be positive because the contributions to the potential from the two positive charges will outweigh the single negative charge's contribution. This is because potential is a scalar quantity and can be added directly without considering the direction, unlike vector quantities like electric fields.