Smpn 95 Jkt - Ulangan Harian Online IPA Kelas 9 Sk 4

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| By Hariyadi95
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Hariyadi95
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Quizzes Created: 4 | Total Attempts: 2,537
Questions: 35 | Attempts: 2,024

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Smpn 95 Jkt - Ulangan Harian Online IPA Kelas 9 Sk 4 - Quiz

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Questions and Answers
  • 1. 

    Berikut ini yang termasuk bahan magnetik dan nonmagnetik adalah ....

    • A.

      Besi dan nikel

    • B.

      Nikel dan baja

    • C.

      Baja dan bismut

    • D.

      Seng dan emas

    Correct Answer
    C. Baja dan bismut
    Explanation
    The correct answer is baja dan bismut. Baja is a magnetic material, as it contains iron, which is a magnetic element. Bismuth, on the other hand, is a nonmagnetic material, as it does not have any magnetic properties. Therefore, both baja and bismuth are examples of materials that belong to the categories of magnetic and nonmagnetic materials respectively.

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  • 2. 

    Garis - garis lengkung yang keluar dari kutub utara menuju kutub selatan  sebuah magnet disebut ....

    • A.

      Kutub magnet

    • B.

      Garis-garis gaya magnet

    • C.

      Medan magnet

    • D.

      Fluks magnet

    Correct Answer
    B. Garis-garis gaya magnet
    Explanation
    The correct answer is "garis-garis gaya magnet." The question is asking for the term used to describe the curved lines that extend from the North Pole to the South Pole of a magnet. These lines are called "garis-garis gaya magnet" in Indonesian, which translates to "magnetic field lines" in English.

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  • 3. 

    Gaya tarik magnet paling kuat terletak pada ....

    • A.

      Seluruh bagian magnet

    • B.

      Salah satu ujung magnet

    • C.

      Bagian ujung-ujung magnet

    • D.

      Bagian tengah magnet

    Correct Answer
    C. Bagian ujung-ujung magnet
    Explanation
    The strongest magnetic pull is located at the ends of a magnet, known as the poles. This is because the magnetic field lines are most concentrated and closely packed at the poles, resulting in a stronger attraction or repulsion. The middle part of the magnet has a weaker magnetic field compared to the ends. Therefore, the answer "bagian ujung-ujung magnet" (ends of the magnet) is correct.

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  • 4. 

    Berikut ini cara membuat magnet, kecuali ....

    • A.

      Cara alami

    • B.

      Cara induksi

    • C.

      Cara menggosok

    • D.

      Cara arus listrik

    Correct Answer
    A. Cara alami
    Explanation
    Cara alami tidak termasuk dalam cara membuat magnet karena magnet alami terbentuk secara alami melalui proses geologi dan tidak melibatkan campur tangan manusia. Sedangkan cara induksi, cara menggosok, dan cara arus listrik adalah metode yang digunakan manusia untuk menciptakan magnet.

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  • 5. 

    Perhatikan gambar berikut. Benda A dapat menarik benda B dan tidak dapat menarik benda C. Pernyataan berikut benar, kecuali ....

    • A.

      Benda A sebuah magnet

    • B.

      Benda B merupakan benda magnetik

    • C.

      Benda C merupakan benda nonmagnetik

    • D.

      Benda C merupakan benda feromagnetik

    Correct Answer
    D. Benda C merupakan benda feromagnetik
    Explanation
    The correct answer is "benda C merupakan benda feromagnetik". This statement is incorrect because the given information states that object A can attract object B but cannot attract object C. This implies that object C is nonmagnetic, not ferromagnetic.

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  • 6. 

    Perhatikan gambar berikut ini. Jika besi/baja telah menjadi magnet, pernyataan berikut benar, kecuali ....

    • A.

      A kutub utara dan B kutub selatan

    • B.

      A kutub selatan dan B kutub utara

    • C.

      A dan B kutub selatan

    • D.

      A dan B kutub utara

    Correct Answer
    B. A kutub selatan dan B kutub utara
    Explanation
    The correct answer is A kutub selatan dan B kutub utara. This is because in a magnet, the north pole (kutub utara) attracts the south pole (kutub selatan) and vice versa. Therefore, it is not possible for A to be kutub selatan and B to be kutub utara.

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  • 7. 

    Ruang atau daerah di sekitar magnet yang masih mempunyai pengaruh gaya tarik magnet disebut ....

    • A.

      Medan magnet

    • B.

      Kutub magnet

    • C.

      Fluks magnetik

    • D.

      Garis-garis gaya magnet

    Correct Answer
    A. Medan magnet
    Explanation
    The correct answer is "medan magnet". The question asks for the term used to describe the area around a magnet that still has the influence of magnetic force. "Medan magnet" translates to "magnetic field" in English, which refers to the region where a magnetic force can be detected.

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  • 8. 

    Elektromagnet (magnet listrik)dapat diperoleh dengan cara ....

    • A.

      Mendekatkan besi/baja pada magnet tetap

    • B.

      Melilitkan kawat berarus listrik DC pada baja/besi berisolasi

    • C.

      Menggosokkan besi/baja dengan magnet tetap ke satu arah.

    • D.

      Melilitkan kawat berarus listrik AC pada besi/baja berisolasi.

    Correct Answer
    B. Melilitkan kawat berarus listrik DC pada baja/besi berisolasi
    Explanation
    By winding a DC electric current wire around an insulated iron/steel, an electromagnet can be obtained.

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  • 9. 

    Jarum kompas selalu menunjuk arah utara selatan bumi, disebabkan adanya ....

    • A.

      Medan magnet bumi

    • B.

      Gravitasi bumi

    • C.

      Gaya tarik bumi

    • D.

      Rotasi bumi

    Correct Answer
    A. Medan magnet bumi
    Explanation
    The compass needle always points towards the north and south of the Earth because of the Earth's magnetic field. The Earth has a magnetic field generated by the movement of molten iron in its outer core. The compass needle aligns itself with the magnetic field lines and points towards the magnetic north pole, which is close to the geographic north pole. This phenomenon is used for navigation purposes, as it allows people to determine their direction relative to the Earth's magnetic field.

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  • 10. 

    Sebuah magnet batang yang tergantung bebas, ternyata tidak menunjuk arah utara selatan sebab ....

    • A.

      Magnet tersebut sifat kemagnetannya sudah lemah

    • B.

      Magnet tersebut berada dalam medan magnet yang lain

    • C.

      Magnet tersebut merupakan magnet sementara

    • D.

      Magnet tersebut tidak memiliki kutub utara dan selatan

    Correct Answer
    B. Magnet tersebut berada dalam medan magnet yang lain
    Explanation
    The correct answer is "magnet tersebut berada dalam medan magnet yang lain". This means that the bar magnet is influenced by another magnetic field, causing it to not point towards the north-south direction.

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  • 11. 

    Daerah pada magnet yang gaya magnetnya terkuat disebut ….

    • A.

      Magnet

    • B.

      Medan magnet

    • C.

      Kutub magnet

    • D.

      Garis gaya magnet

    Correct Answer
    C. Kutub magnet
    Explanation
    The correct answer is "kutub magnet". This is because the region on a magnet where the magnetic force is the strongest is called the magnetic pole or "kutub magnet" in Indonesian. The magnetic field lines converge at these poles, indicating the concentrated strength of the magnetic field in that area.

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  • 12. 

    Daerah di sekitar magnet yang terdapat gaya-gaya magnet disebut ….

    • A.

      Kutub magnet

    • B.

      Medan magnet

    • C.

      Garis gaya magnet

    • D.

      Magnet elementer

    Correct Answer
    B. Medan magnet
    Explanation
    The correct answer is "medan magnet". Medan magnet refers to the region around a magnet where magnetic forces are present. It is the area where the magnetic field is exerted and can be felt. This field is created by the magnet and extends into the surrounding space. Therefore, medan magnet is the term used to describe the area around a magnet where magnetic forces are experienced.

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  • 13. 

    Dari bahan-bahan berikut, yang bukan bahan magnetik adalah ….

    • A.

      Gelas

    • B.

      Besi

    • C.

      Kobalt

    • D.

      Nikel

    Correct Answer
    A. Gelas
    Explanation
    Gelas bukanlah bahan magnetik karena tidak memiliki sifat tarik-menarik terhadap benda-benda logam seperti besi, kobalt, dan nikel.

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  • 14. 

    Jika jarak antara dua kutub magnet dijauhkan, maka gaya magnet yang timbul ….

    • A.

      Tetap

    • B.

      Menjadi nol

    • C.

      Bertambah

    • D.

      Berkurang

    Correct Answer
    D. Berkurang
    Explanation
    When the distance between two magnets is increased, the magnetic force between them decreases. This is because the strength of the magnetic field diminishes with distance. As the magnets move farther apart, the magnetic field lines spread out and become less concentrated, resulting in a weaker magnetic force. Therefore, the correct answer is "berkurang" which means "decreases" in English.

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  • 15. 

    Jika magnet batang dipotong menjadi tiga bagian, maka bagian yang tengah ….

    • A.

      Tidak bersifat magnet

    • B.

      Hanya memiliki kutub utara

    • C.

      Hanya memiliki kutub selatan

    • D.

      Memiliki kutub utara dan selatan

    Correct Answer
    D. Memiliki kutub utara dan selatan
    Explanation
    When a bar magnet is cut into three pieces, each piece will still have a north and south pole. This is because the magnetic properties of a magnet are not lost when it is divided. Therefore, the correct answer is that the middle piece will have both a north and south pole.

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  • 16. 

    Sudut antara jarum kompas dengan arah utara selatan sebenarnya disebut ….

    • A.

      Inklinasi

    • B.

      Deklinasi

    • C.

      Kutub

    • D.

      Bumi

    Correct Answer
    B. Deklinasi
    Explanation
    The correct answer is "deklinasi." Deklinasi refers to the angle between the compass needle and the true north-south direction. It is a measure of the magnetic declination, which is the difference between magnetic north and true north. This angle is important for navigation purposes, as it helps determine the correct compass heading to follow. The term "inklinasi" refers to the inclination or tilt of the Earth's magnetic field, "kutub" refers to the poles, and "Bumi" means Earth.

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  • 17. 

    Benda A dapat menarik benda B dan tidak dapat menarik benda C. pernyataan yang benar adalah :

    • A.

      Benda A ferromagnetik

    • B.

      Benda B diamagnetik

    • C.

      Benda C diamagnetik

    • D.

      Benda ABC adalah magnet

    Correct Answer
    C. Benda C diamagnetik
    Explanation
    The correct answer is "Benda C diamagnetik". This means that object C is diamagnetic, which implies that it is not attracted to a magnetic field. This is in contrast to object B, which is also diamagnetic but is attracted to a magnetic field. Object A is ferromagnetic, meaning it can attract other magnetic materials. The statement "Benda ABC adalah magnet" is not correct because it implies that all three objects are magnets, which is not stated in the given information.

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  • 18. 

    Oersted melakukan eksperimen dengan mendekatkan kawat berarus listrik di dekat magnet, ternyata  jarum magnet bergerak. Dapat disimpulkan bahwa :

    • A.

      Di sekitar kawat berarus listrik terdapat medan magnet

    • B.

      Di sekitar kawat berarus listrik terdapat medan listrik

    • C.

      Arah medan magnet tidak ditentukan oleh arah arus listrik

    • D.

      Arah medan magnet searah dengan arah arus listrik

    Correct Answer
    A. Di sekitar kawat berarus listrik terdapat medan magnet
    Explanation
    The correct answer is "di sekitar kawat berarus listrik terdapat medan magnet" (there is a magnetic field around the current-carrying wire). This is because Oersted's experiment showed that when a current-carrying wire is placed near a magnet, the magnet's needle moves. This indicates that there is a magnetic field present around the wire, which interacts with the magnet. The other options are incorrect because there is no mention of an electric field or the direction of the magnetic field being determined by the direction of the current.

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  • 19. 

    Perhatikan gambar elektromagnet berikut, jika logam PQ adalah besi, pernyataan yang benar adalah …

    • A.

      P kutub utara, Q kutub selatan

    • B.

      P kutub selatan, Q kutub utara

    • C.

      Kemagnetan sulit diubah-ubah

    • D.

      Magnet PQ akan menjadi magnet permanen

    Correct Answer
    A. P kutub utara, Q kutub selatan
    Explanation
    The correct answer is "P kutub utara, Q kutub selatan". This means that pole P is the north pole and pole Q is the south pole. This is because in an electromagnet, the north pole is formed at the end where the current flows in a counterclockwise direction, while the south pole is formed at the end where the current flows in a clockwise direction. Therefore, in this case, pole P is the north pole and pole Q is the south pole.

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  • 20. 

    Besarnya gaya Lorentz yang dialami penghantar berarus listrik di dalam medan magnet ditentukan oleh      beberapa faktor, kecuali ….

    • A.

      Besarnya kuat arus

    • B.

      Panjang kawat

    • C.

      Luas penampang kawat

    • D.

      Kuat medan magnet

    Correct Answer
    C. Luas penampang kawat
    Explanation
    The Lorentz force experienced by a current-carrying conductor in a magnetic field is determined by several factors, including the magnitude of the current, the length of the wire, and the strength of the magnetic field. However, the area of the wire's cross-section does not affect the magnitude of the Lorentz force.

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  • 21. 

    Sebuah kawat penghantar sepanjang 10 m berarus listrik 2 A yang berada dalam medan magnet 20 Tesla, maka gaya Lorent yang bekerja sebesar ….

    • A.

      4 N

    • B.

      40 N

    • C.

      400 N

    • D.

      4000 N

    Correct Answer
    C. 400 N
    Explanation
    The Lorentz force is given by the equation F = qvB, where F is the force, q is the charge, v is the velocity, and B is the magnetic field. In this case, the wire is carrying a current of 2 A, which is equivalent to a charge of 2 C per second. The velocity of the charge carriers in the wire is assumed to be the same as the drift velocity, which is typically very small. Therefore, we can assume that the velocity is negligible compared to the speed of light. The force can then be calculated as F = (2 C/s)(10 m)(20 T) = 400 N.

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  • 22. 

    Kelompok alat berikut ini yang bekerja berdasarkan elektromagnet adalah ….

    • A.

      Bel listrik, telepon, kompor listrik

    • B.

      Telepon, galvanometer, relai

    • C.

      Relai, motor listrik, akumulator

    • D.

      Setrika listrik, akumuloator, galvanometer

    Correct Answer
    B. Telepon, galvanometer, relai
    Explanation
    The correct answer is "Telepon, galvanometer, relai". These three devices work based on the principle of electromagnetism. In a telephone, an electric current is used to generate an electromagnetic signal that carries sound. A galvanometer uses an electromagnet to measure electric current. A relay uses an electromagnet to control the flow of electricity in a circuit.

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  • 23. 

    Alat yang banyak manfaatnya bagi manusia modern yang prinsip kerjanya berdasarkan induksi elektromagnetik adalah ....

    • A.

      Generator

    • B.

      Alternator

    • C.

      Transformator

    • D.

      A dan C benar

    Correct Answer
    D. A dan C benar
    Explanation
    The correct answer is "A dan C benar" (A and C are correct). This means that both the generator and transformer have many benefits for modern humans and work based on electromagnetic induction. Generators convert mechanical energy into electrical energy, while transformers are used to change the voltage of an alternating current. Therefore, both A (generator) and C (transformer) are correct answers.

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  • 24. 

    Transformator tidak dapat digunakan untuk mengubah tegangan arus searah karena .....

    • A.

      Tegangannya berubah – ubah

    • B.

      Kuat arusnya terlalu kecil

    • C.

      Tegangannya tidak dapat diubah – ubah

    • D.

      Tidak terjadi perubahan jumlah garis gaya magnet

    Correct Answer
    D. Tidak terjadi perubahan jumlah garis gaya magnet
    Explanation
    A transformer works based on the principle of electromagnetic induction, which requires a changing magnetic field to induce a voltage in the secondary coil. In the case of direct current (DC), there is no change in the magnetic field because the current flows in one direction continuously. Therefore, a transformer cannot be used to change the voltage of a DC current.

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  • 25. 

    Transformator tidak dapat digunakan untuk ....

    • A.

      Memperbesar tegangan listrik

    • B.

      Memperkecil tegangan listrik

    • C.

      Memperbesar daya listrik

    • D.

      Memperbesar kuat arus listrik

    Correct Answer
    C. Memperbesar daya listrik
    Explanation
    A transformer cannot be used to increase power because power is the product of voltage and current. A transformer can only change the voltage level of an alternating current, either stepping it up or stepping it down, but it cannot change the power. The power output of a transformer is equal to the power input, minus any losses due to inefficiency. Therefore, the correct answer is that a transformer cannot be used to increase power.

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  • 26. 

    Transformator bekerja berdasarkan prinsip induksi elektromagnetik yang ditemukan oleh ...

    • A.

      Oersted

    • B.

      Faraday

    • C.

      Lorentz

    • D.

      Ohm

    Correct Answer
    B. Faraday
    Explanation
    The correct answer is Faraday. A transformer works based on the principle of electromagnetic induction, which was discovered by Michael Faraday. He found that a changing magnetic field can induce an electric current in a nearby conductor. In a transformer, alternating current in the primary coil creates a changing magnetic field, which then induces a current in the secondary coil. This allows for the transfer of electrical energy between different voltage levels.

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  • 27. 

    Efisiensi transformator adalah hasil bagi antara ....

    • A.

      Daya sekunder dengan daya primer

    • B.

      Daya primer dengan daya sekunder

    • C.

      Daya primer dengan jumlah lilitan primer

    • D.

      Jumlah lilitan primer dengan jumlah lilitan sekunder

    Correct Answer
    A. Daya sekunder dengan daya primer
    Explanation
    Efisiensi transformator adalah hasil bagi antara daya sekunder dengan daya primer. Ini berarti efisiensi transformator dihitung dengan membagi daya keluaran transformator (daya sekunder) dengan daya masukan transformator (daya primer). Efisiensi transformator menunjukkan seberapa efisien transformator dalam mentransfer daya dari sumber input ke beban output. Semakin tinggi efisiensi transformator, semakin efisien transformator dalam mengubah daya listrik.

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  • 28. 

    Hal berikut yang berlaku pada trafo ideal adalah ....

    • A.

      Daya masukan > daya keluaran

    • B.

      Efisiensi > 90%

    • C.

      Daya masukan sama denga daya keluaran

    • D.

      Banyak mengalamki kebocoran fluks magnetik

    Correct Answer
    C. Daya masukan sama denga daya keluaran
    Explanation
    The correct answer is "daya masukan sama dengan daya keluaran." In an ideal transformer, the input power is equal to the output power. This means that the transformer does not experience any power losses, making it highly efficient. In an ideal transformer, all the electrical energy supplied to the primary coil is transferred to the secondary coil without any losses.

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  • 29. 

    Sebuah trafo step down mempunyai kumparan primer 1200 lilitan dihubungkan dengan tegangan input 120 V. Kumparan sekunder memberikan out out 9 volt. Jika efisiensi trafo 100%, jumlah lilitan kumparan sekunder adalah ...

    • A.

      16000 lilitan

    • B.

      1080 lilitan

    • C.

      900 lilitan

    • D.

      90 lilitan

    Correct Answer
    D. 90 lilitan
    Explanation
    The primary coil of the transformer has 1200 turns and is connected to an input voltage of 120 V. The secondary coil gives an output of 9 volts. The efficiency of the transformer is given as 100%. To find the number of turns in the secondary coil, we can use the formula for transformer voltage ratio: Vp/Vs = Np/Ns. Since the efficiency is 100%, the input power is equal to the output power. Therefore, VpIp = VsIs. Substituting the given values, we get 120*Ip = 9*Is. Since the voltage ratio is 120/9, the turns ratio is also 120/9. Therefore, Np/Ns = 120/9 = 40/3. Solving for Ns, we get Ns = Np/(40/3) = 1200/(40/3) = 90 turns.

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  • 30. 

    Tegangan maksimum generator listrik AC tergantung pada .... (1) kecepatan sudut putar rotornya (2) besar induksi magnet yang digunakan (3) jumlah lilitan rotornya (4) luas bidang lilitan rotornya Pernyataan diatas yang benar adalah ...

    • A.

      1,2 dan 3

    • B.

      1 dan 3

    • C.

      2 dan 4

    • D.

      4 saja

    Correct Answer
    A. 1,2 dan 3
    Explanation
    The maximum voltage of an AC electric generator depends on the speed of rotation of its rotor, the magnitude of the magnetic induction used, and the number of windings in the rotor. These factors affect the electromagnetic induction process, which generates the voltage in the generator. Therefore, options 1, 2, and 3 are correct as they all contribute to determining the maximum voltage of the generator. Option 4, which only mentions the area of the rotor winding, is not correct as it does not directly affect the maximum voltage.

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  • 31. 

    Untuk menyalakan lampu 10 volt dengan tegangan listrik dari PLN 220 volt digunakan transformator step down. Jika jumlah lilitan primer transformator 1.100 lilitan, berapakah jumlah lilitan pada kumparan sekundernya ?

    • A.

      50 lilitan

    • B.

      100 lilitan

    • C.

      5000 lilitan

    • D.

      1000 lilitan

    Correct Answer
    A. 50 lilitan
    Explanation
    The correct answer is 50 lilitan. The question states that a step-down transformer is used to power a 10 volt lamp with electricity from a 220 volt PLN. The primary coil of the transformer has 1,100 turns. The number of turns in the secondary coil can be determined using the formula:

    (Vp/Vs) = (Np/Ns)

    Where Vp is the voltage of the primary coil, Vs is the voltage of the secondary coil, Np is the number of turns in the primary coil, and Ns is the number of turns in the secondary coil.

    In this case, Vp = 220 volts, Vs = 10 volts, and Np = 1,100 turns. Solving for Ns, we get:

    (220/10) = (1,100/Ns)

    22 = 1,100/Ns

    Ns = 1,100/22

    Ns = 50

    Therefore, the number of turns in the secondary coil is 50 lilitan.

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  • 32. 

    Sebuah transformator step down mempunyai jumlah lilitan primer 1000 dan lilitan sekunder 200, digunakan untuk menyalakan lampu 12 V, 48 W. Tentukan arus listrik sekunder !

    • A.

      4 A

    • B.

      0,8 A

    • C.

      40 A

    • D.

      8 A

    Correct Answer
    A. 4 A
    Explanation
    A step-down transformer is used to decrease the voltage from the primary side to the secondary side. In this case, the primary winding has 1000 turns and the secondary winding has 200 turns. The power of the lamp is given as 48W and the voltage is 12V. To determine the secondary current, we can use the formula P = IV, where P is the power, I is the current, and V is the voltage. Rearranging the formula to solve for I, we get I = P/V. Substituting the given values, we get I = 48W / 12V = 4A. Therefore, the correct answer is 4 A.

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  • 33. 

    Sebuah transformator mempunyai efisiensi 80%. Jika lilitan primer dihubungkan dengan tegangan 200 V dan mengalir kuat arus listrik 5 A. Tentukan daya primernya ?

    • A.

      10 watt

    • B.

      100 watt

    • C.

      1000 watt

    • D.

      10.000 watt

    Correct Answer
    C. 1000 watt
    Explanation
    The power of the primary coil can be calculated using the formula P = V x I, where P is the power, V is the voltage, and I is the current. In this case, the voltage is 200 V and the current is 5 A. Therefore, the power of the primary coil is 200 V x 5 A = 1000 watt.

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  • 34. 

    Sebuah trafo memiliki perbandingan lilitan 10 : 2 dihubungkan ke sumber listrik 100V untuk menyalakan sebuah lampu 25 W. Hitunglah tegangan listrik yang diserap oleh lampu !

    • A.

      2 V

    • B.

      20 V

    • C.

      1 V

    • D.

      10 V

    Correct Answer
    B. 20 V
    Explanation
    The given transformer has a turns ratio of 10:2, which means that for every 10 turns on the primary coil, there are 2 turns on the secondary coil. The transformer is connected to a 100V power source. The power consumed by the lamp is given as 25W. To find the voltage absorbed by the lamp, we can use the formula: Power = Voltage^2 / Resistance. Since the resistance of the lamp is not given, we can assume it to be constant. Therefore, the voltage absorbed by the lamp can be calculated as follows: Voltage = sqrt(Power * Resistance). Since the resistance is constant, the voltage absorbed by the lamp will be proportional to the square root of the power. In this case, since the power is 25W, the voltage absorbed by the lamp will be sqrt(25) = 5V. However, since the transformer steps up the voltage, the voltage absorbed by the lamp will be multiplied by the turns ratio. Therefore, the voltage absorbed by the lamp will be 5V * (10/2) = 25V. Therefore, the correct answer is 20V.

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  • 35. 

    Sebuah trafo memiliki perbandingan lilitan kumparan 10:1 dihubung-kan ke listrik 100 V untuk menyalakan sebuah lampu 7,5 W. Jika efisiensi trafo 75 %, berapakah arus listrik pada kumparan primer ?

    • A.

      0,1 A

    • B.

      1 A

    • C.

      10 A

    • D.

      100 A

    Correct Answer
    A. 0,1 A
    Explanation
    The given question provides information about a transformer with a turns ratio of 10:1, connected to a 100 V power source to power a 7.5 W lamp. The efficiency of the transformer is stated to be 75%. The question asks for the current in the primary coil.

    To solve this, we can use the formula for power: Power = Voltage x Current. Given that the power output is 7.5 W and the voltage is 100 V, we can calculate the current in the secondary coil using this formula.

    Since the transformer has an efficiency of 75%, we can assume that the power input is 75% of the power output. Therefore, the power input is 7.5 W / 0.75 = 10 W.

    Using the formula again, we can calculate the current in the primary coil. The power input is 10 W and the voltage is 100 V, so the current in the primary coil is 10 W / 100 V = 0.1 A.

    Therefore, the correct answer is 0.1 A.

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  • Current Version
  • Mar 21, 2023
    Quiz Edited by
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  • Feb 27, 2013
    Quiz Created by
    Hariyadi95
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