Final answer:
The electric flux through a square of 3.2 mm on each side in a uniform electric field of magnitude E=18000 N/C at an angle of 35° with the normal line is 0.9 N·m²/C.
Step-by-step explanation:
To find the electric flux through the surface of a square immersed in a uniform electric field, you can use the equation Φ = E * A * cos(θ), where Φ is the electric flux, E is the magnitude of the electric field, A is the area of the surface, and θ is the angle between the electric field and the normal to the surface.
The square has a side length of 3.2 mm (which is 3.2 x 10-3 meters), so the area A = (3.2 x 10-3 m)2. The electric field E is given as 18000 N/C. The angle θ is 35° from the normal. Therefore, the electric flux Φ = 18000 N/C * (3.2 x 10-3 m)2 * cos(35°).
Calculating the cosine of 35° and then calculating Φ, we find:
Φ = 18000 * (3.2 x 10-3)2 * cos(35°).
Φ = 18000 * (1.024 x 10-5) * 0.8192.
Φ = 0.9 N·m2/C.
Therefore, the correct answer is C. 0.9 N·m2/C.