Question

Given a uniform electric field `vecE=4xx10^(3)hati N//C`. Find the flux of this field through a square of side 5cm on a side whose plane is parallel to the y-z plane. What would be the flux through the same square, if the plane makes a `30^(@)` angle of with the x-axis?

Answer 1

When the plane is parallel to the y-z plane :
Electric flux,
`phi=vecE vecA`
Here,`" "vecE=4xx10^(3)hati`
`vecE=4xx10^(3)hati N//CA=0.25 xx10^(-2)hati m^(2)`
`therefore" "phi=4xx10^(-2)hati. 25 xx10^(-4)hati`
`rArr" "phi=10" weber "(10Nm^(2)C^(-1))`
When the plane makes a `30^(@)` angle with x-axis the area vector makes a `60^(@)` angle with the x-axis.
`phi=vecE vecA rArr phi = EA cos theta` ltbr. `rArr" "4xx10325 xx10^(-4)cos 60^(@)`
`rArr" "phi=10^(2)`
`rArr" "phi=".5 weber "(5 Nm^(2)C^(-1))`