Final answer:
The flux through the cube when you have two charges: q1 located at y = 1/2a and the second charge q2 can be calculated using Gauss's Law (Option A).
Step-by-step explanation:
The net flux through the cube can be calculated using Gauss's Law. Gauss's Law states that the flux through a closed surface is equal to the total charge enclosed divided by the permittivity of the vacuum. In this case, since we have two charges, q1 and q2, we can calculate the flux due to each charge separately and then use the principle of superposition to find the net flux.
To calculate the flux due to q1, we need to consider the cube's face that is parallel to the yz-plane. Since q1 is located at y = 1/2a, the flux due to q1 through this face will be zero because the electric field lines are perpendicular to the surface.
To calculate the flux due to q2, we need to consider the cube's face that is parallel to the xz-plane. Since q2 is located at an unspecified position, we cannot determine the flux due to q2 without more information.
Therefore, the correct option to calculate the flux through the cube is (a) Gauss's Law.