Q:

Gauss's law, electrical flux density

Q. Given a 60-μC point charge located at origin, find the total electrical flux passing through the plane z = 26 cm.

I can understand what the question means, but I can't do anything.
Is it using with gauss's law? then how can I find closed S? Because the z plane is infinite.
Could you explain this Question physical-intuition?
Also solve this problem using Gauss's law please.

A:

This is one of those questions which very much relies on the fact that the plane is infinite.   So any electric field line which starts off going towards the plane will be counted as part of the electric flux through the plane.
Any electric field line which has a z component must reach the infinite z=26 cm plane.

