How Is Electric Flux Calculated Through a Tilted Surface?

[daimoku]

[SOLVED] Flux through a surface

Homework Statement

The square surface shown in Figure 24-26 measures 3.8 mm on each side. It is immersed in a uniform electric field with magnitude |E| = 2000 N/C. The field lines make an angle of 35° with a normal to the surface, as shown. Take that normal to be directed "outward," as though the surface were one face of a box. Calculate the electric flux through the surface.

http://personalpages.tds.net/~locowise/test/24-26.gif

E=2000N/C
theta=(180-35)=145
A=(0.0038m)^2=1.444*10^-5 m^2

Homework Equations

flux=EAcos(theta)

The Attempt at a Solution

flux=2000N/C * (1.444*10^-5 m^2) cos145 = -0.023657 N*m^2/C

 

[G01]

Your answer is correct, and your work looks sound. Do you have any other questions?

 

[Moetasim]

I would like to point out that the unit for electric flux is actually N*m^2/C, not N*m^2/C^2 as written in the attempted solution. Additionally, the negative sign in front of the calculated value indicates that the flux is directed inward, rather than outward as assumed in the problem statement. This could be due to a misunderstanding of the direction of the electric field lines, as they are actually directed toward the negative charges, rather than away from them. Overall, the calculation for the flux through the surface appears to be correct.