GAUS'S LAW
use when
When you are given some charge
distribution and you want to find the
eletric field.
electric flux,ΦE
is
the number of
field lines crossing a given surface
∅E=∮E.dA = ∮EdA
Application of Gauss's Law
state:
the electric flux through any closed surface is equal
to the charge enclosed divided by the permittivity of free space
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∅=∮E .dA=qin/(ε˳)
1)Determine the electric field pattern
2)choose the gaussian surface
3)workout the surface intergral
4)decide qin
5)set ∅=qin/(ε˳)
An alternative way to describe electric field and electric force other than coulomb's law
Enclosed charge only
Depends on
if
-there is a positive net flux there is a net
positive charge enclosed
-there is a negative flux there is a net
negative charge enclosed
-there is a zero net flux there is no net
charge enclosed
To measure how much an electric field through some arbitrary surface area.
Area
EA=σ/ε˳
E=0
inside conductors
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conductors in electrostatic equilibrium