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STATIC ElectricBy Mr. Joe
For SMABELS StundentONLY
Learning’s Menu
Physics Is
Funny!
OBJECTIVES
SUBJECT
QUIZ
Objectives• Explain the concept of electric charge and
its interaction.• Explain that an object can be electrically
charged by being rubbed• Calculate the interactional force between
electric charges by using Coulombs law.• Explain the concept of electric field
STATIC ELECTRIC
Why is plastic ruler that is rubbed on hair can pull little papers?
Listrik Tidak Mengalir
To get answer question upon us need to understand about atom.
Litle Paper tear
Plastic ruler
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Atomic Model 1. Atom Hidrogen ( H )
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2. Atom Helium ( He ) 3. Atom Litium ( Li )
How many proton on Helium upon? How many elektron on Helium upon?
What is Helium atom gets electricity?
How many proton on Lithium atom upon?
How many electron on Lithium atom upon?
What is Lithium atom gets electricity?
Why is Helium atom neutral?
Why is Lithium atom neutral?
Conclusion if which atom was said by neutral?
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Plastic that rubbed by woolen clothes, therefore plastic wills be get negative electricity, since woolen’s electron migrant to plasctic.
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Getting electricity on object by rubs
glass that rubbed by silk therefore glass wills be get positive electricity, since glass electron migrant goes to silk.
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Getting electricity on object by rubs
Interaction among electricity
like charges repel each other
repeled
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Interaction among electricity
attrated
unlike charges attract each other.
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Coulombs lawKlik
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• The force between two charges is equal to Coulomb’s constant, times the product of the two charges, divided by the square of the distance between them.
221
r
qqkF
F = coulomb force( N )
q = charge ( C )
r = distance ( m )
k = coulomb constanta
Satuan SI Cgs
F N dyne
Q C Stc
r m cm
K Nm2/C2 dyne cm2/ Stc2
Nilai 9.109Nm2/C2 1 dyne cm2/ Stc2
Example • Two charges Q1 and Q2, have 3µC dan –
2 µC are separated by a distance 10 cm if Coulombs Constanta is 9.109 N m2/C2 What total force are them?
221.
R
QQkF
2
66229
)01,0(
10.2.10.3/10.9
m
CCCNmF
)0001,0(
10.2.10.3/10.9
2
66229
m
CCCNmF
24
66229
10
10.2.10.3/10.9
m
CCCNmF
F = 54 N
Catatan
Ubah satuan – satuan besaran yang ada kedalan satuan SI
μC = 10 –6 C
cm =10 –2 m
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Electric fieldThe electric field is the space around an electrical charge which is still influenced by the object’s electric charge.
E
The more far the location of the test object from charged objects Q then the force gets smaller influence so strong electric field is getting smaller
E
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Coulomb force’s Lines• Electric field figured by Coulomb force’s
lines.
Direction of electric lines of force charge positif, leaving a charge
Direction of electric lines of force charge negative, toward the charge
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The pattern on the electric lines of force
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Strong electric fields
Q q
rE
Benda bemuatan listrik Q didekatkan benda uji bermuatan q berjarak r Besar kuat medan listrik di titik benda uji adalah gaya listrik yang ditimbulkan benda bermuatan di bagi muatan uji
qr
QqkE
2
q
FE
2r
QkE
E = electric field ( N/C )
Q = Source Charge ( C )
q = test charge ( C )
r = distance ( m )
F = Coulomb Force ( N )
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Electrostatic Induction
Conclusion:Elctrostatic induction is the phenomenon where electric charge separate in neutral object when a object closed by elictric charge.
Netral
What happens to the charge neutral object ,when approached by a positively charged object?
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Getting negative electricity on object with induction
Neutral
Neutral objects when induced by positively charged objects will become negatively charged
Bumi
Negatif charge
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Getting a positive electric charge on an object by induction
Neutral
Neutral objects when induced by negatively charged objects will become positively charged
Bumi
Positif charge
Conclusion type objects induced charge opposite to the type of content objects that induce
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Getting a negative electric charge by touching objects.
Neutral
Neutral objects when touched by a negatively charged object will become negatively charged
Negatif charge
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How do we explain when a neutral object when the object is positively charged touched the neutral object become positively charged?
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Elektoscope• The instrument used to determine the electrical
charge on the object.
Elektroscope heaad
conduktor
Elektroscope leaf
Glass wall
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Karya Kreatif
Tujuan : Membuat Elektroskop SederhanaAlat & bahan :
1. Botol bekas kecil2. Alluminium foil (bekas bungkus rokok )3. Kawat tembaga 15 cm4. Amplas5. Gabus6. penggaris plastik
Langkah – langkah1. Ambil Alluminium fiol bekas bungkus rokok dan
pisahkan kertas yang menempel pada Alluminium dengan cara membakarnya hingga Alluminium bersih dari kertas yang menempel.
2. Potong Alluminium foil dengan ukuran 0.5 cm x 4 cm
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3. Amplas kedua ujung kawat tembaga dan tekuk salah satu ujung kawat tembaga hingga berbentuk seperti gambar.
4. Letakkan potongan Alluminium foil pada ujung kawat tembaga yang telah ditekuk lalu lipat Alluminium foil tersebut seperti gambar.
5. Masukkan kawat tembaga yang telah diberi Alluminium foil ke dalam botol dan tutup botol dengan gabus seperti gambar.
6. Remas Alluminium foil dan tancapkan pada ujung tembaga yang diluar botol7. Gosokkan penggaris plastik pada rambut dan dekatkan pada kepala
elektroskop yang telah kamu buat amati apa yang terjadi dengan daun elektrokop ?
3 cm
3 cm
Di amplas
1 3 52 4
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Electroscope working principles:
at neutral electroscope leaves covered
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at Charged electroscope leaves covered
Electricity on electroscope with induction
Netral Electroscope head closeed by positively charged object, electron from leaf moves to head and electroscope leaf opens
Electroscope head is touched out hand therefore electron from earth go to lectroscope and counteracts electroscope leaf, therefore electroscope leaf close
Electroscope negatively charged become since accepts electron from earth
Jenis muatan benda terinduksi berlawanan dengan jenis muatan benda yang menginduksi
Bagaimana kalau yang didekatkan pada kepala elektoskop benda bermuatan negatif Jelaskan !
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Kilat
Because the house has a huge barrier when the electrons pass through a large number of houses will be damaged, which means that the house was struck by lightning.
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Prinsip Kerja Penangkal Petir 1Klik
Ketika rumah terinduksi oleh awan yang bermuatan sehinga atap rumah menjadi bermuatan positif maka muatan – muatan negatif awan mengalir dari awan kebumi melewati penamgkal petir, karena penangkal petir terbuat dari bahan konduktor yang baik maka ketika dilewati muatan listrik negatif dari awan tidak menyebabkan kerusakan.
Penangkal petir
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Prinsip Kerja Penangkal Petir 2 Ketika rumah terinduksi oleh awan yang bermuatan sehinga atap rumah dan penangkal petir menjadi bermuatan positif karena penangkal petir terbuat dari bahan konduktor yang ujungnya runcing maka udara disekitar penangkal petir akan terionisasi ion negatif akan ketarik penangkal petir dan dialirkan kebumi sedangkan ion positif akan ketarik awan dan menetralkan awan .
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Penangkal petir
Generator Van de Graff• Mesin pembangkit listrik
statis yang sangat besar
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Sabuk karet
logam
Politen
Prisip kerja
Gesekan antara silinder logam dengan sabuk karet menghasilkan muatan listrik negatif pada sabuk karet dan muatan negatif dialirkan ke bola konduktor.
Bola konduktor akan bermuatan negatif yang sangat besar.
Gesekan antara politen dengan sabuk karet menyebabkan sabuk karet nemjadi bermuatan positif karena sabuk karet yang bermuatan positif dihubungkan dengan bumi maka elektron dari bumi menetralkan muatan positif pada sabuk karet.
TAGIHAN SOAL 1Pemahaman Konsep1. Lengkapi nama – nama partikel penyusun atom pada model atom di bawah
Model atom …………………….
……………………. …………………….
…………………….
2. Atom natrium ( Na ) dan atom klor ( Cℓ ) yang semula netral kemudian karena sesuatu hal satu buah elektron terluar dari atom natrium pindah ke atom klor menyebabkan atom natrium kehilangan ………… dan menjadi bermuatan ……………, sedagkan atom klor menerima …………… dan menjadi bermuatan ………………
3. Kaca yang digosok dengan kain sutra menjadi bermuatan listrik dan ditetapkan jenis muatannya adalah ……………………..Jelaskan secara listrik statis kaca dapat ermuatan listrik tersebut !
4. Gaya apa yang muncul ketika plastic bermuatan yang digantung pada statif didekati dengan kaca bermuatan yang kita pegang tangan …………………
5. Faktor apa yang mempengaruhi besar gaya listrik antara muatan …………6. Gambar arah medan listrik pada dua muatan positif yang berdekatan ?7. Apa yang dimaksud dengan Induksi listrik
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• Kinerja Ilmiah1. Lengkapi gambar peristiwa induksi di bawah dengan menambahkan
muatan yang terdapat pada kepala dan daun elektroskopnya serta jelaskan terjadinya dengan teori listrik statis ?a. b.
2. Jelaskan mengapa balon yang digosok – gosok dengan kain dapat menempel pada kaca
3. Jelaskan prinsip kerja alat penangkal petir sesuai konsep listrik static.
4. Dua buah muatan listrik yang masing-masing 4 C dan 3 C menimbulkan gaya listrik sebesar 8 N, jika jarak antara kedua muatan diperbesar menjadi 2 kali semula berapakah besar gaya listrik yang muncul sekarang ?
5. Dua bola kecil yang bermuatan listrik sama dan sejenis digantung dengan tali seperti gambar. Jika besar gaya tolak yang muncul antara kedua muatan 0,1 N dan k = 9.109 N m2/C2 berapakah besar muatan masing-masing ?
3 cm
1. Glass rubbed on silk will be positively charged because ....a. Electron move from the glass to silkb. Proton move from the glass to silkc. Electron move from silk to glassd. Proton move from silk to glass
2. The attractive or repulsive force betwwen two electric charge is ....e. Inversely proportional to their chargesf. Directly proportional to the square of their chargesg. Inversely proportional to the square of intercharge
distanceh. Directly proportional to the square of intercharge
distance
Quiz
3. Two electric charge, q1 and q2, at a certain distance (r), produce repulsive force F. If q1 is changed five times larger and the distance of two charge changed three times larger, the repulsive force becomes ....a.5/3 F b.5/6 Fc.5/9 Fd.9/5 F
4. Two object have electric charge of 2 x 10-5 C and 5 x 10-6 C is separated at a distance of 3 cm. If the constant k = 9 x 109 N m2/C2, the force between two object is equal ....a.1 Nb.10 Nc.100 Nd.1000 N
An object with electric charge
Interaction
X Y Repel each otherX Z Attract each otherY Z ...........
5. Look at the table below.
The interaction between Y and Z is ....a. Repel each otherb. Attract each otherc. No effect at alld. neutral
6. The interaction between two charges is F. If the distance of two charges becomes twice as much, their electric force is ....a. 0.20 F
b. 0.25 F
c. 0.40 F
d. 0.50 F
7. The region around electric charge that is still influenced by elektric force is called ....
a. Electric field
b. Coulomb’s force
c. Electric potential
d. Magnetic field•
8. Electric field strength is ....a. Force per unit area
b. Force per unit charge
c. Work per unit area
d. Work per unit charge
9. Study the statement below.
1. Disimilar electric charge repel each other
2. An object will be negatively charged if the number of electron is more than the number of protons
3. Disimilar electric charge attract each other
4. An object will be positively charged if the number of electron is more than the number of protons
The correct statements ....
a. 1 and 2
b. 1 and 3
c. 2 and 3
d. 2 and 4
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10. Consider the statements below.
1. Field lines never cross each other
2. Field lines always go inward approaching a negative charge
3. Field lines always go outward approaching a negative charge
4. Field lines always go outward approaching a positive charge
5. The correct statements of electric field is shown by numbers ....
a. 1, 2, and 3
b. 1, 3, and 4
c. 2, 3, and 4
d. 1, 2, and 4
Subject
