Chapter 5.3, Problem 2dT

The three spherical Gaussian surfaces at right each enclose a charge $+Q_o$ . In case C there is another charge $-6Q_o$ , outside the surface.

Consider the following conversation:

Student 1: “Since each Gaussian surface encloses the same charge, the net flux through each must be the same.”

Student 2: “Gauss’ law doesn't apply here. The electric field at the Gaussian surface in case B is weaker than in case A, because the surface is farther from the charge. Since the flux is proportional to the electric field strength, the flux must also be smaller in case."

Student 3: "I was comparing A and C. In C the charge outside changes the field over the whole surface. The areas are the same, so the flux must be different.”

Do you agree with any of the student's? Explain.