A point charge of 200 μC moves from point A to a point B in an electric field, the work done by the electric force is 8×10⁻⁴ J. Calculate:
a) The potential difference between points A and B;
b) The electric potential taking B as a reference.

An electric field is produced in a vacuum by two point charges of 2 μC and 5 μC. Calculate:
a) The electric potential, at a point P, which is 0.2 m from the first charge and 0.5 m from the second;
b) The electric potential energy that a charge q = 6×10⁻⁸ C acquires when placed at P.

An electric field is produced in a vacuum by two point charges of −2 μC and 5 μC. Calculate:
a) The electric potential, at a point P, which is 0.2 m from the first charge and 0.5 m from the second;
b) The electric potential energy that a charge q = 6×10⁻⁸ C acquires when placed at P.

Determine the electric potential at point P in cases (A), (B), and (C) of the figure below, Q = 6 μC, \( k_e=9\times 10^9\;\mathrm{\frac{N.m^2}{C^2}} \) , and given the distances of the charges to point P:
a) d_A = 0.3 m;
b) d_B = 0.1 m;
c) d_C = 0.2 m.