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Pertemuan V Dasar Teknik Elektro Resistor, Capasitor dan Induktor.

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Presentasi berjudul: "Pertemuan V Dasar Teknik Elektro Resistor, Capasitor dan Induktor."— Transcript presentasi:

1 Pertemuan V Dasar Teknik Elektro Resistor, Capasitor dan Induktor

2 Resistors Resistors can be either fixed or variable in value Resistors can be either fixed or variable in value Fixed resistors come in a variety of different shapes, sizes and forms Fixed resistors come in a variety of different shapes, sizes and forms Axial lead resistors have the value of resistance printed on them or as a colour code Axial lead resistors have the value of resistance printed on them or as a colour code Surface mount resistors have a numerical code indicating a value Surface mount resistors have a numerical code indicating a value All resistors have a tolerance value All resistors have a tolerance value

3 Resistors Variable resistors are called potentiometers Variable resistors are called potentiometers There is a fixed value of resistance between two terminals There is a fixed value of resistance between two terminals The moving part of the potentiometer is called the wiper The moving part of the potentiometer is called the wiper

4 Resistors Four band resistor colour code Four band resistor colour code 1st band provides the first digit of the code 1st band provides the first digit of the code 2nd band provides the second digit of the code 2nd band provides the second digit of the code 3rd band is the multiplier 3rd band is the multiplier 4th band indicates the tolerance value 4th band indicates the tolerance value

5 Resistors Resistor colour code calculation The first band red has a value of 2 The first band red has a value of 2 The second band purple has a value of 7 The second band purple has a value of 7 The third band has a multiplier of x 10 The third band has a multiplier of x 10 The last band indicates a tolerance value of +/-5% The last band indicates a tolerance value of +/-5% Resistance value is 270Ω +/-5% Resistance value is 270Ω +/-5% 2 7 x10 +/-5%

6 Resistors in Series and Parallel Circuits

7 Resistors in circuits To determine the current or voltage in a circuit that contains multiple resistors, the total resistance must first be calculated. To determine the current or voltage in a circuit that contains multiple resistors, the total resistance must first be calculated. Resistors can be combined in series or parallel. Resistors can be combined in series or parallel.

8 Resistors in Series When connected in series, the total resistance (Rt) is equal to: When connected in series, the total resistance (Rt) is equal to: Rt = R 1 + R 2 + R 3 +… The total resistance is always larger than any individual resistance. The total resistance is always larger than any individual resistance.

9 Sample Problem 10 V 15 Ω 10 Ω 6 Ω Calculate the total current through the circuit. Rt = 15 Ω +10 Ω + 6 Ω Rt = 31 Ω I = V/R t = 10 V/ 31 Ω = 0.32 A

10 Since charge has only one path to flow through, the current that passes through each resistor is the same. Since charge has only one path to flow through, the current that passes through each resistor is the same. The sum of all potential differences equals the potential difference across the battery. The sum of all potential differences equals the potential difference across the battery. Resistors in Series 10 V 5 V 3 V 2 V

11 Resistors in Parallel When connected in parallel, the total resistance (Rt) is equal to: When connected in parallel, the total resistance (Rt) is equal to: 1/Rt = 1/R 1 + 1/R 2 + 1/R 3 +… Due to this reciprocal relationship, the total resistance is always smaller than any individual resistance. Due to this reciprocal relationship, the total resistance is always smaller than any individual resistance.

12 Sample Problem 12 Ω 4 Ω 6 Ω Calculate the total resistance through this segment of a circuit. 1/Rt = 1/12 Ω +1/4 Ω + 1/6 Ω = 1/12 Ω + 3/12 Ω + 2/12 Ω = 1/12 Ω + 3/12 Ω + 2/12 Ω 1/R t = 6/12 Ω = ½ Ω Rt = 2 Ω

13 Since there is more than one possible path, the current divides itself according to the resistance of each path. Since there is more than one possible path, the current divides itself according to the resistance of each path. smallest resistor = more current passes largest resistor = least current passes largest resistor = least current passes Resistors in Parallel

14 The voltage across each resistor in a parallel combination is the same. The voltage across each resistor in a parallel combination is the same. Resistors in Parallel 10 V

15 Calculate the total resistance in the circuit below +- 3 Ω 2 Ω 6 Ω 4 Ω R tot = 3 Ω + 2 Ω = 5 Ω R tot = 6 Ω + 4 Ω = 10 Ω 1/R tot = 2/10 Ω+ 1/10 Ω = 3/10 Ω R tot = 3 1/3Ω

16 KAPASITOR dan DIELEKTRIK

17 Contoh-contoh Capacitor

18

19 Pengertian Kapasitor Dua penghantar berdekatan yang dimaksudkan untuk diberi muatan sama tetapi berlawanan jenis disebut kapasitor. Dua penghantar berdekatan yang dimaksudkan untuk diberi muatan sama tetapi berlawanan jenis disebut kapasitor. Sifat menyimpan energi listrik / muatan listrik. Sifat menyimpan energi listrik / muatan listrik. Kapasitas suatu kapasitor (C) adalah perbandingan antara besar muatan Q dari salah satu penghantarnya dengan beda potensial V antara kedua pengahntar itu. Kapasitas suatu kapasitor (C) adalah perbandingan antara besar muatan Q dari salah satu penghantarnya dengan beda potensial V antara kedua pengahntar itu.

20 Kegunaan Kapasitor Untuk menghindari terjadinya loncatan listrik pada rangkaian2 yang mengandung kumparan bila tiba2 diputuskan arusnya. Untuk menghindari terjadinya loncatan listrik pada rangkaian2 yang mengandung kumparan bila tiba2 diputuskan arusnya. Rangkaian yang dipakai untuk menghidupkan mesin mobil Rangkaian yang dipakai untuk menghidupkan mesin mobil Untuk memilih panjang gelombang yang ditangkap oleh pesawat penerima radio. Untuk memilih panjang gelombang yang ditangkap oleh pesawat penerima radio. Bentuk kapasitor Kapasitor bentuk keping sejajar Kapasitor bentuk keping sejajar Kapasitor bentuk bola sepusat Kapasitor bentuk bola sepusat Kapasitor bentuk silinder Kapasitor bentuk silinder

21 DIELEKTRIK Dielektrik adalah suatu lempengan tipis yang diletakkan di antara kedua pelat kapasitor. Jika di antara keping + dan keping – diisi dengan bahan dielektrik (isolator), kuat medan listrik di antara keping akan menurun dan kapasitansi akan naik. Beberapa alasan penggunaan dielektrik adalah :  Memungkinkan untuk aplikasi tegangan yang lebih tinggi (sehingga lebih banyak muatan).  Memungkinkan untuk memasang pelat menjadi lebih dekat (membuat d lebih kecil).  Memperbesar nilai kapasitansi C karena K>1.

22 Dengan adanya suatu lembaran isolator (“dielectric”) yang ditempatkan di antara kedua pelat, kapasitansi akan meningkat dengan faktor K, yang bergantung pada material di dalam lembaran. K disebut sebagai konstanta dielektrik dari material. dielectric Karenanya C = K  0 A / d secara umum adalah benar karena K bernilai 1 untuk vakum, dan mendekati 1 untuk udara. Kita juga dapat mendefinisikan  = K  0 dan menuliskan C =  A / d.  disebut sebagai permitivitas dari material C = K  0 A / d

23 Kapasitas Kapasitor Bila luas masing2 keping A, maka : Tegangan antara kedua keping : Jadi kapasitas kapasitor untuk ruang hampa adalah : q-q A d E

24 Bila di dalamnya diisi bahan lain yang mempunyai konstanta dielektrik K, maka kapasitasnya menjadi Hubungan antara C 0 dan C adalah : Kapasitor akan berubah kapasitasnya bila : K, A dan d diubah K, A dan d diubah Dalam hal ini C tidak tergantung Q dan V, hanya merupakan perbandingan2 yang tetap saja. Artinya meskipun harga Q diubah2, harga C tetap.

25 Hubungan Kapasitor a. Hubungan Seri Kapasitor yang dihubungkan seri akan mempunyai muatan yang sama.

26 b. Hubungan Paralel Kapasitor yang dihubungkan paralel, tegangan antara ujung2 kapasitor adalah sama, sebesar V.

27 Energi Kapasitor Sesuai dengan fungsinya, maka kapasitor yang mempunyai kapasitas besar akan dapat menyimpan energi yang lebih besar pula. Persamaannya :

28 KAPASITOR Secara umum Kapasitor terdiri atas dua keping konduktor yang saling sejajar dan terpisah oleh suatu bahan dielektrik ( dari bahan isolator) atau ruang hampa. Bahan dielektrik Antara dua keping dihubungkan dengan beda potensial  V dan menimbulkan muatan listrik sama besar pada masing-masing keping tetapi berlawanan tanda. Sumber Gambar : Haliday-Resnick-Walker Luas =A

29 Kapasitor Sifat Kapasitor Sifat Kapasitor 1. Dapat menyimpan energi listrik, tanpa disertai reaksi kimia 2. Tidak dapat dilalui arus listrik DC dan mudah dilalui arus bolak-balik 3. Bila kedua keping dihubungkan dengan beda potensial, masing- masing bermuatan listrik sama besar tapi berlawanan tanda. Hal.: 29 Isi dengan Judul Halaman Terkait Simbol Kapasitor + V +Q -Q

30 Kapasitor Kapasitas kapasitor (C) menunjukkan besar muatan listrik pada masing-masing keping bila kedua keping mengalami beda potensial 1 volt Kapasitas kapasitor (C) menunjukkan besar muatan listrik pada masing-masing keping bila kedua keping mengalami beda potensial 1 volt Hal.: 30 Isi dengan Judul Halaman Terkait + V +Q -Q V Q = nilai muatan listrik pada masing- masing keping V = beda potensial listrik antar keping ( volt) C = kapasitas kapasitor (Farad = F )

31 Kapasitas kapasitor Hal.: 31 Ruang hampa atau udara Luas =A C = kapasitas kapasitor (Farad= F) d = Jarak antar keping (meter) A = luas salah satu permukaan yang saling berhadapan (meter 2 )  o = permitivitas udara atau ruang hampa ( · C/vm )

32 Kapasitas kapasitor Hal.: 32 Bahan dielektrik Luas =A  = permitivitas bahan dielektrik ( C/vm ) Kapasitas kapasitor yang terdiri atas bahan dielektrik K = tetapan dielektrik (untuk udara atau ruang hampa K = 1 )

33 Rangkaian Kapasitor Rangkaian seri Rangkaian seri Hal.: 33 + V +Q 1 -Q 1 +Q 2 -Q 2 1.Kapasitas gabungan kapasitor (C g ), kapasitas kapasitor pertama (C 1 ), kapasitor kedua (C 2 ) memenuhi : 2.Muatan listrik yang tersimpan pada rangkaian = muatan listrik pada masing- masing kapasitor. Q = Q 1 + Q 2 dan Q 1 = Q 2 3.Tegangan listrik antar ujung rangkaian(V), tegangan pada kapasitor pertama(V 1 ) dan kapasitor kedua(V 2 ) memenuhi: V = V 1 + V 2 1.Kapasitas gabungan kapasitor (C g ), kapasitas kapasitor pertama (C 1 ), kapasitor kedua (C 2 ) memenuhi : 2.Muatan listrik yang tersimpan pada rangkaian = muatan listrik pada masing- masing kapasitor. Q = Q 1 + Q 2 dan Q 1 = Q 2 3.Tegangan listrik antar ujung rangkaian(V), tegangan pada kapasitor pertama(V 1 ) dan kapasitor kedua(V 2 ) memenuhi: V = V 1 + V 2

34 Rangkaian Kapasitor Rangkaian seri Rangkaian seri Hal.: 34 + V = 6 volt +Q -Q +Q -Q C 1 = 2  FC 2 = 3  F Contoh 1. Kapasitas gabungan kapasitor : C g = 6/5 = 1,2  F 2. Muatan listrik pada rangkaian = 1,2  F x 6V = 7,2  C Pada kapasitor satu = 7,2  C Pada kasitor kedua = 7,2  C 3. Tegangan liatrik pada kapasitor satu = 3,6 V Pada kapasitor dua = 2,4 V 1. Kapasitas gabungan kapasitor : C g = 6/5 = 1,2  F 2. Muatan listrik pada rangkaian = 1,2  F x 6V = 7,2  C Pada kapasitor satu = 7,2  C Pada kasitor kedua = 7,2  C 3. Tegangan liatrik pada kapasitor satu = 3,6 V Pada kapasitor dua = 2,4 V

35 Rangkaian Kapasitor Rangkaian paralel Rangkaian paralel Hal.: 35 + V +Q 1 -Q 1 +Q 2 -Q 2 1.Tegangan pada kapasitor pertama (V 1 ), kapasitor kedua (V 2 ) dan tegangan sumber (V) masing-masing sama besar. V 1 = V 2 = V 2.Muatan listrik yang tersimpan pada rangkaian memenuhi Q = Q 1 + Q 2 3.Kapasitas gabungan kapasitor mmenuhi : C g = C 1 + C 2

36 Rangkaian Kapasitor Rangkaian paralel Rangkaian paralel Hal.: 36 Isi dengan Judul Halaman Terkait + +Q 1 -Q 1 +Q 2 -Q 2 1.Tegangan pada kapasitor pertama (V 1 ) dan kapasitor kedua (V 2 ) adalah V 1 = V 2 = 6 volt 2.Kapasitas gabungan kapasitor adalah C g = C 1 + C 2 = 2  F + 3  F = 5  F 3.Muatan listrik yang tersimpan pada rangkaian memenuhi Q = C g xV = 5  F x 6V = 30  C Q 1 = C 1 x V = 2  Fx6V = 12  C Q 2 = C 2 x V = 3  Fx6V = 18  C Contoh C 1 = 2  F C 2 = 3  F V = 6 volt

37 Energi Listrik yang Tersimpan pada Kapasitor Grafik hubungan tegangan (V) dengan muatan listrik yang tersimpan pada kapasitor (Q) Grafik hubungan tegangan (V) dengan muatan listrik yang tersimpan pada kapasitor (Q) Hal.: 37 Isi dengan Judul Halaman Terkait V(volt) Q(Coulomb) Q V Nilai energi listrik yang tersimpan pada kapasitor yang bermuatan listrik Q = luas daerah Dibawah garis grafik Q-V (yang diarsir ).

38 Energi Listrik yang Tersimpan pada Kapasitor Hal.: 38 Isi dengan Judul Halaman Terkait + V Sebuah kapasitor yang memiliki kapasitas C dihubungkan dengan tegangan V. C Karena Q = C.V, maka W = Energi listrik yang tersimpan pada kapasitor ( Joule ) Keterangan : Q = muatan listrik kapasitor ( Coulomb) C = Kapasitas kapasitor ( farad) V = tegangan listrik antar keping kapasitor ( Volt)

39 Inductors Energy Storage Devices

40 Objective of Lecture Describe Describe The construction of an inductor The construction of an inductor How energy is stored in an inductor How energy is stored in an inductor The electrical properties of an inductor The electrical properties of an inductor Relationship between voltage, current, and inductance; power; and energy Relationship between voltage, current, and inductance; power; and energy Equivalent inductance when a set of inductors are in series and in parallel Equivalent inductance when a set of inductors are in series and in parallel

41 Inductors Generally - coil of conducting wire Generally - coil of conducting wire Usually wrapped around a solid core. If no core is used, then the inductor is said to have an ‘air core’. Usually wrapped around a solid core. If no core is used, then the inductor is said to have an ‘air core’.

42 Symbols

43 Alternative Names for Inductors Reactor- inductor in a power grid Reactor- inductor in a power grid Choke - designed to block a particular frequency while allowing currents at lower frequencies or d.c. currents through Choke - designed to block a particular frequency while allowing currents at lower frequencies or d.c. currents through Commonly used in RF (radio frequency) circuitry Commonly used in RF (radio frequency) circuitry Coil - often coated with varnish and/or wrapped with insulating tape to provide additional insulation and secure them in place Coil - often coated with varnish and/or wrapped with insulating tape to provide additional insulation and secure them in place A winding is a coil with taps (terminals). A winding is a coil with taps (terminals). Solenoid – a three dimensional coil. Solenoid – a three dimensional coil. Also used to denote an electromagnet where the magnetic field is generated by current flowing through a toroidal inductor. Also used to denote an electromagnet where the magnetic field is generated by current flowing through a toroidal inductor.

44 Energy Storage The flow of current through an inductor creates a magnetic field (right hand rule). The flow of current through an inductor creates a magnetic field (right hand rule). If the current flowing through the inductor drops, the magnetic field will also decrease and energy is released through the generation of a current. If the current flowing through the inductor drops, the magnetic field will also decrease and energy is released through the generation of a current. B field

45 Sign Convention The sign convention used with an inductor is the same as for a power dissipating device. When current flows into the positive side of the voltage across the inductor, it is positive and the inductor is dissipating power. When the inductor releases energy back into the circuit, the sign of the current will be negative.

46 Current and Voltage Relationships L, inductance, has the units of Henries (H) L, inductance, has the units of Henries (H) 1 H = 1 V-s/A

47 Power and Energy

48 Inductors Stores energy in an magnetic field created by the electric current flowing through it. Stores energy in an magnetic field created by the electric current flowing through it. Inductor opposes change in current flowing through it. Inductor opposes change in current flowing through it. Current through an inductor is continuous; voltage can be discontinuous. Current through an inductor is continuous; voltage can be discontinuous. %20Basic%20Navy%20Training%20Courses/electricity%20-%20basic%20navy%20training%20courses%20- %20chapter%2012.htm

49 Calculations of L For a solenoid (toroidal inductor) N is the number of turns of wire A is the cross-sectional area of the toroid in m 2.  r is the relative permeability of the core material  o is the vacuum permeability (4π × H/m) l is the length of the wire used to wrap the toroid in meters

50 Wire Unfortunately, even bare wire has inductance. d is the diameter of the wire in meters.

51 Properties of an Inductor Acts like an short circuit at steady state when connected to a d.c. voltage or current source. Acts like an short circuit at steady state when connected to a d.c. voltage or current source. Current through an inductor must be continuous Current through an inductor must be continuous There are no abrupt changes to the current, but there can be abrupt changes in the voltage across an inductor. There are no abrupt changes to the current, but there can be abrupt changes in the voltage across an inductor. An ideal inductor does not dissipate energy, it takes power from the circuit when storing energy and returns it when discharging. An ideal inductor does not dissipate energy, it takes power from the circuit when storing energy and returns it when discharging.

52 Properties of a Real Inductor Real inductors do dissipate energy due resistive losses in the length of wire and capacitive coupling between turns of the wire. Real inductors do dissipate energy due resistive losses in the length of wire and capacitive coupling between turns of the wire.

53 Inductors in Series

54 L eq for Inductors in Series

55 Inductors in Parallel

56 L eq for Inductors in Parallel

57 General Equations for L eq Series Combination Parallel Combination If S inductors are in series, then If P inductors are in parallel, then:

58 Summary Inductors are energy storage devices. Inductors are energy storage devices. An ideal inductor act like a short circuit at steady state when a DC voltage or current has been applied. An ideal inductor act like a short circuit at steady state when a DC voltage or current has been applied. The current through an inductor must be a continuous function; the voltage across an inductor can be discontinuous. The current through an inductor must be a continuous function; the voltage across an inductor can be discontinuous. The equation for equivalent inductance for The equation for equivalent inductance for inductors in series inductors in parallel inductors in series inductors in parallel


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