1. The problem statement, all variables and given/known data I am given a vector field associated with a square area of a certain side, lets call this side dx, centered on the x-axis at a certain point, say x = x1. The sides of this cross sectional square are parallel to the axis of y and z. I have to compute the flux of this vector field, or rather, the vector surface integral. Now I understand how to set up the equation, substitute the relevant variables, and such. What I'm not totally certain of is how to determine the upper and lower limits over the z and y paths. Also, what does the unit vector, n, do? 2. Relevant equations ᶴ V n dS, where dS = dydz, and V and n are vectors. 3. The attempt at a solution As I said, I have already set up the (double) integral according to the above formula, but I need to determine the limits of the definite integral.