A uniform electric field of magnitude E = 100 N/C exists in the space in X-direction. What is the flux of this field through a plane square area of edge 10 cm placed in the Y-Z plane? Take the normal along the positive X-axis to be positive

1 N-m²

The flux Φ = ∫ E.cosθ ds.

As the normal to the area points along the electric field, θ = 0.