Answer:
[tex]\phi = 1.28 Nm^2/C[/tex]
Explanation:
As we know that electric flux is defined as
[tex]\phi = \vec E . \vec A[/tex]
now we have
[tex]A = L^2[/tex]
[tex]A = 0.80^2 = 0.64 m^2[/tex]
[tex]E = 3.5 N/C[/tex]
also we know that electric field makes and angle of 35 degree with surface
so angle made by electric field with Area vector is given as
[tex]\theta = 90 - 35 = 55[/tex]
[tex]\phi = EAcos\theta[/tex]
[tex]\phi = (3.5)(0.64)cos55[/tex]
[tex]\phi = 1.28 Nm^2/C[/tex]