Static Electricity

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Static Electricity
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Sumber Gambar Fisika SMK Teknologi, Direektorat
SMK
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Phenomenons 0f Static electricity
Hard ruber stick, a Stick of glass or a ruler of
plastic is scrubed in cloth
Plastic ruler is scrubed in dry hair
Phenomenons 0f Static electricity
Iron nyilon cloth
and all that
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Electric Charge

• Anything is scrubed in different thing with the
  result that static electricity, so thing is
  called containt electric charge.

Two plastic rulers and two glass sticks are
scrubed by drugget so each are be charge
The two of ruler mutual refuse to averse
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Electric Charge
The two of glass sticks mutual refuse to averse
A plastic ruler and a glass stick are trade-offs
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Electric Charge
Everything that is pulled glass so pussed away
plastic ruler
Everything that is pussed away glass so pulled
plastic ruler
The Phenomenons show there are two kinds of
electric charges
Franklin choose electric charges in glass as
positive charges, and electric charges in plastic
as negative charges. On time the treaty still are
used
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Electric Charge
Have symbol Q or q
SI unit electric charge is Coulomb (C)
Electric Charge
Elementary charge is 1,6 x 10 -19 C
The charge on a single electron is -1.6 x 10 -19
Coulomb
The charge on a single proton is 1.6 x 10 -19
Coulomb
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CoulombS Law
F12 force at particle 1 by particle 2 ( Newton
) F 21 force at particle 2 by particle 1
(Newton ) r the distance of separation
between the two objects (meters ) k
a proportionality constant known as the
Coulomb's law constant
is dependent upon the medium that the charged
objects are immersed in
k
In the case of air vacuum , the value is
approximately 9,0 x 109 Nm2 / C2
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CoulombS Law
Value k (constanta ) besides air or vacuum
? permitivitas a media
?o permitivitas of air or vacuum
K dielectrik constanta For air or vacuum K 1
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Hukum Coulomb
F
F
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Hukum Coulomb
Contoh soal
On the air found two electricity charge 10 µC and
40 µC and apart in distance 20 cm

• How much is big load second interaction force?
• When does second load laided at a medium that has
  dilelectric
• constant 3, how much is force that
  undergone by 40 µC ?

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Hukum Coulomb
Penyelesaian
a.
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Hukum Coulomb
b.
30 N
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The electric field

• An electric field is said to exist in the region
  of space around a charged object. When another
  charged object enters this electric field, an
  electric force acts on it.

A convenient way of visualizing electric field
patterns is to draw lines that follow the same
direction as the electric field vector at any
point. These lines, called electric field lines
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Electric field E
The number of lines per unit area through a
surface perpendicular to the lines is
proportional to the magnitude of the electric
field in that region
E
Electric field lines penetrating two surfaces.
The magnitude of the field is greater on surface
A than on surface B
Sumber Halliday-Resnick-Walker
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Magnitude of the Electric Field
the electric field E at a point in space is
defined as the electric force F acting on a
positive test charge q placed at that point
divided by the magnitude of the test charge
.
E
E electric field ( N/C)
q electricity charg (Coulomb)
F static electricity charge (Newton)
it has value
belong Vector QUANTITIES
Elctric field
it has direction
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Electric Field direction at a Point

• Electricity field intensity direction is
  unidirectional and correlating to squeez with the
  electric force F acting on a positive test charge
  q placed at that point divided by the magnitude
  of the test charge

B
.
E
A

.
E
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Electric Field aroud negative electricity Charge
B
.
E
A
-
.
E
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Electric Field in area between two electricity
charge
At point C doesnt has electric field
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Electric Field in area between two electricity
charge
There is a point between two electricity charge
that has strongest Electric Field
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The Eletric Field Around Electricity Charge

• The electric field at a point, such as A, that
  has distance of electrical charge particale as Q

In order to determine electric filed at point A
we put electricity charge as q at point A.

A
.
Q
r
E
Q


k
q
r 2
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Electric Flux
Field lines representing a uniform electric field
penetrating a plane of area A perpendicular to
the field.
The electric flux E through this area is equal to
EA
? E x A
Sumber Haliday Resnick, 745
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Electric Flux
When area A is at an angle ? to the field
? E x A cos ?
Sumber Haliday Resnick, 745
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Gausss Law
The net flux through any closed surface
surrounding a point charge q is given by q/?o
Karl Friedrich Gauss
(17771866)
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Gausss Law
the net electric flux through a closed surface
that surrounds no charge is zero
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Hukum Gaus
If E is perpendicular to area A, so
? E x A
Q electrical charge in closed surface
( Coulomb )
Q
E x A
? charge density ( C/m2 )
?o
?
Q

E
E
?o
?o
A
?o permitivitas of air or vacuum 8,85 x
10-12 C2 N-1m-2