Gauss Law

The electric flux Φ through a surface

• is the amount of electric field piercing the surface
• is the electric field multiplied by the area.
• does not depend on the area involved
• is the line integral of the electric field around the edge of the surface

The area vector for a flat surface

• is parallel to the surface and has a magnitude equal to the length of a side of the surface.
• is perpendicular to the surface and has a magnitude equal to the length of a side of the surface.
• is parallel to the surface and has a magnitude equal to the area of the surface.
• is perpendicular to the surface and has a magnitude equal to the area of the surface.

When a piece of paper is held with one face perpendicular to a uniform electric field the flux through it is 25 N×m²/C. When the paper is turned 25° with respect to the field the flux through it is: 

• 0 N×m²/C
• 11 N×m²/C
• 12 N×m²/C
• 23 N×m²/C

Tags

NGSS.HS-PS2-4

A physics instructor in an anteroom charges an electrostatic generator to 25 mC, then carries it into the lecture hall. The net electric flux through the lecture hall walls is: 

• 0 N×m²/C
• 25 x 10^–6 N×m²/C
• 2.2 x 10⁵ N×m²/C
• 2.8 x 10⁹ N×m²/C

A point particle with charge q is placed inside a cube but not at its center.  The electric flux through any one side of the cube:

• is zero
• is q/2ε₀
• is q/4ε₀
• is q/6ε₀