Q.
Consider a uniform electric field E=3×103i^N/C. What is the flux of this field through a square of 10cm on a side whose plane is parallel to the y−z plane?
Here, E=3×103i^N/C
i.e., field is along +x -axis direction.
Surface area, S=(10cm)2=102cm2 =102×10−4m2=10−2m2.
When plane is parallel to y−z plane, θ=0∘ ϕE=EScosθ=3×103×10−2cos0∘ =30NC−1m2