Question

Given a uniform electric field `vecE=5xx10^(3)hatiN//C`, find the flux of this field through a square of 10cm 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 with the x-axis?

Answer 1

When the plane is parallel to the y-z plane :
Electric flux, `phi=EA`
Here `vecE=5xx10^(3) hati N//CA=10cm^(2) hati=10^(-2) hati m^(2),phi=5xx10^(3)hati. 10^(-2)hati rArr phi=50` weber.
When the plane makes a `30^(@)` angle with the x-axis, the area vector makes `60^(@)` with the x-axis,
`phi=E.A rArr phi=E A cos theta`
`rArr" "phi=5xx10^(3).10^(-2)cos 60^(@)`
`rArr" "phi=50xx(1)/(2)rArr phi=25Wb.`