Electric flux

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

A cylindrical wastepaper basket with a 0.15-m radius opening is in a uniform electric field of 300 N/C, perpendicular to the opening. The total flux through the sides and bottom is: 

• 0 N×m²/C
• 4.2 N×m²/C
• 21 N×m²/C
• 280 N×m²/C

Tags

NGSS.HS-PS3-5

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

Which quantity and unit are correctly paired?

• electric field strength and N/C
• electricity and Coulombs
• electrostatic force and electrons
• electric field strength and E

Tags

NGSS.HS-PS2-4

When is the flux on a surface zero?

• When it is perpendicular to an electric field

• When it is at an angle to an electric field

• When it is parallel to an electric field

• It is never zero in an electric field

A charge is sitting outside a closed surface. The net flux is

• double because it passes through two surfaces

• half because it passes through two surfaces

• squared because it passes through two surfaces

• zero because it passes through two surfaces

SEE IMAGE

• A

• B

• C

• D

• E

SEE IMAGE

• A

• B

• C

• D

• E

Tags

NGSS.HS-PS2-5

NGSS.HS-PS3-5