Final answer:
The potential at the joining points of diagonals in an octagon with equal charges at each vertex is a non-zero constant value due to the scalar nature of potential and the symmetry of the configuration.
the potential at the joining points of diagonals will be: a) Zero
Step-by-step explanation:
If charge is kept on each vertex of an octagon, the electric potential at the joining points of diagonals would be a non-zero constant value. Each charge on the vertices of the octagon would contribute to the potential at that point, but because of symmetry, the contributions from opposite vertices would cancel each other out in terms of the electric field (not the potential).
Since potential is a scalar quantity and does not cancel out the way vector quantities like the electric field do, the result is a non-zero value that is the same for any such joining point of diagonals within the octagon.
The potential at the joining points of diagonals of an octagon will be non-zero constant value.
This is because each vertex of the octagon will have a charge, and the potential at a point is the sum of the potentials due to all charges in the system.
Since each charge contributes to the potential, the total potential at the joining points of diagonals will not be zero, but rather a constant value determined by the charges on the vertices.