kuliah 4: potensial listrik " the world little knows how many of the thoughts and theories...
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Kuliah 4: Potensial listrikKuliah 4: Potensial listrik
"The world little knows how many of the thoughts and theories which have passed through the mind of the scientific investigator have been crushed in silence and secrecy by his own severe criticism and adverse examination; that in the most successful instances not a tenth of the suggestions, the hopes, the wishes, the preliminary conclusions have been realized."
--Michael Faraday
Michael Faraday (1791-1867)
Physics 102 Section 202 Copyright by Dr. Marina Milner-Bolotin
2
Potensial listrik: Potensial listrik:
Gaya Elektrostatika Gaya Gravitasi
Medan dan energi Medan dan energi
Medan listrik seragamMedan listrik seragam:
PE=qEdPE=qEd
Medan listrik seragam :Medan listrik seragam :
PE = mghPE = mgh
Energi potensial: muatan titikEnergi potensial: muatan titik Energi potensial: massa titikEnergi potensial: massa titik
Potensial: Muatan titikPotensial: Muatan titik Potensial: Massa titikPotensial: Massa titik
r
mmGPE 21
r
qqkPE 21
b
a
ab ldFUU
b
a
ab ldFUU
r
mGpotentialGrav .
r
qkV
Physics 102 Section 202 Copyright by Dr. Marina Milner-Bolotin
3
B
ABAAB dWUUU lF
Physics 102 Section 202 Copyright by Dr. Marina Milner-Bolotin
4
1. Ua = Ub > Uc = Ud 2. Ua = Uc > Ub = Ud 3. Ub = Ud > Ua = Uc 4. Ud > Ub = Uc > Ua 5. Ud > Uc > Ub > Ua
r
qqU 21
0
21 q
4
1
r
kq
Energi potensial listrikEnergi potensial listrik
Physics 102 Section 202 Copyright by Dr. Marina Milner-Bolotin
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Potensial listrikPotensial listrik
r
kQV
r
kQ
r
kQdr
r
kQVV
r
kQE
ldEVV
ldq
F
q
U
q
U
ldFUU
ab
b
a
ab
b
a
ab
b
a
ab
b
a
ab
infinityat 0V If
)(22
000
Physics 102 Section 202 Copyright by Dr. Marina Milner-Bolotin
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Grafik VGrafik V
Physics 102 Section 202 Copyright by Dr. Marina Milner-Bolotin
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Permukaan ekuipotensialPermukaan ekuipotensial
r
qqU
r
q
21
0
21
0
q
4
1
r
kq
4
1
r
kqV
Physics 102 Section 202 Copyright by Dr. Marina Milner-Bolotin
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Permukaan ekuipotensialPermukaan ekuipotensial
Two positive charges repelling each other (weak field in between)
Two unlike charges attracting each other (strong field in between and weak field outside)
Physics 102 Section 202 Copyright by Dr. Marina Milner-Bolotin
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Urutkan potensial terbesar --terkecil
1. ∆V12 > ∆V13 = ∆V23 2. ∆V13 > ∆V12 > ∆V23 3. ∆V13 > ∆V23 > ∆V12 4. ∆V13 = ∆V23 > ∆V12 5. ∆V23 > ∆V12 > ∆V13
Potensial listrik pada muatan titikPotensial listrik pada muatan titik
Physics 102 Section 202 Copyright by Dr. Marina Milner-Bolotin
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Bola bermuatan: E and VBola bermuatan: E and V
E = 0 pada bola bermuatan
Physics 102 Section 202 Copyright by Dr. Marina Milner-Bolotin
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Permukaan ekuipotensialPermukaan ekuipotensial
E = 0
V = const
rkVr
rkV
r
qkV
4
4 2
Physics 102 Section 202 Copyright by Dr. Marina Milner-Bolotin
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Contoh 2: E dan V oleh muatan titikContoh 2: E dan V oleh muatan titik
Physics 102 Section 202 Copyright by Dr. Marina Milner-Bolotin
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Jawab :Jawab :
m
Ck
m
CkV
m
Ck
m
CkV
r
kQ
r
kQV
VVV
A
A
QAQAA
QAQAA
6.0
)1050(
6.0
)50(
3.0
)50(
6.0
)50(
6
2_
2
1_
1
__ 21
04.0
)50(
4.0
)50(2_
2
1_
1
__ 21
B
B
QBQBB
QBQBB
Vm
Ck
m
CkV
r
kQ
r
kQV
VVV
r
qkV
Physics 102 Section 202 Copyright by Dr. Marina Milner-Bolotin
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Jawab :Jawab :
Ax
Ay
AyAxA
yA
xA
yQAyQAyA
xQAxQAxA
QAQAA
E
E
EEE
m
Ck
m
CkEy
m
CkEx
EEEy
EEEx
EEE
)tan(
)sin(6.0
)50(
3.0
)50(:
0)cos(6.0
)50(:
:
:
22
22
2
__
21
21
21
y
x
EQ2
EQ1
EE
EE
EQ2
EQ1