Page 26 - Electrostatics 11
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Grade 11 © GC Shiba
☻ What is electric flux? State and explain Gauss law in electrostatics.
Use it to find electric field intensity due to infinite plane sheet of
charge.
Electric intensity due to charged plane sheet
Let us consider a positively
charged plane sheet having surface
charge density σ .( σ =
charge/surface area). We are
interested to find the electric
intensity at point P outside the
charged plane sheet at a distance r.
A cylindrical Gaussian surface PP'
of cross-sectional area A through
P is drawn as shown in figure.
The total electric flux passing through the two flat surfaces at the ends of PP' is
= 2 .
Since net charge enclosed by the area A is σ A, so by Gauss's theorem,
ℎ
=
∈ 0
, 2 . =
∈ 0
=
2 0
Clearly, E is independent of r, remains the same and does not change
with distance from the conductor. The field lines remain everywhere
straight, parallel and equally spaced.
26 Electrostatics
