A uniform electric field points in the positive x direction and has a magnitude of $40\mathrm{N}/\mathrm{C}$. What is the net flux through a cube with sides $4.0\mathrm{cm}$? The cube has one corner on the origin and the positive x, y, and z axes form three of its edges.

The electric flux through each surface of a cube is given below. Which surfaces of the cube does the electric field run parallel to? 

Φ₁ = 100 Nm² /C      Φ₄ = 0 Nm² /C

Φ₂ = 20 Nm² /C       Φ₅ = −40 Nm² /C

Φ₃ = 0 Nm² /C        Φ₆ = −80 Nm² /C

Where does the normal vector point for a spherical shell?

What is the total flux through the two surfaces depicted in the following figure? Note that surface 1 has an area of 50 cm² and surface 2 has an area of 100 cm² , and E = 500 N/C.