Consider a uniform electric field `bar(E)=3 xx10^(3) NC^(-1)`. What is the flux of this field through a square of 10 cm on a side whose plane is parallel to the YZ plane?

Explanation

Given `vec(E)=3xx10^(3) hat(i) N//C`
As the surface is in Y - Z plane, so the area vector (normal to the square) is along X -axis.
Area `S=10xx10=100 cm^(2)=10^(-2) m^(2)`.
Area vector `vec(S)=10^(-2) hat(i) m^(2)`
`phi=vec(E).vec(S)=(3xx10^(3) hat(i)).(10^(-2) hat(i))`
`:. phi =3xx10^(3) xx10^(-2) =30N-m^(2)`/c `[ :' hat(i).hat(i)=1]_(z)^(2)`