Forum Diskusi 1-2 Electric Charge and Electric Field) [PDF]

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Forum diskusi untuk topik electric charge and electric field Thread 2: soal pilihan ganda 200 soal Verifikasi jawaban dari setiap soal yang diberikan( Bgmn anda memperoleh jawaban tsb) Soal



1. A coulomb is the same as: A) an ampere/second B) half an ampere  second2 C) an ampere/meter2 D) an ampere second E) a newton meter2 Ans: D Difficulty: E I = Q/t ; Arus = Muatan/Waktu 1 amp = 1 coulomb/ 1 sec Jadi 1 coulumb sama dengan ampere times second. 2. A kiloampere  hour is a unit of: A) current B) charge per time C) power D) charge E) energy Ans: D Difficulty: E kA. hr = I x t = Q Q= charge 3. The magnitude of the charge on an electron is approximately: A) 1023 C B) 10–23 C C) 1019 C D) 10–19 C E) 109 C Ans: D Difficulty: E Muatan elektron setara dengan besar muatan unsur (e). negatif. Karena nilai muatan unsur (e) kira-kira = 1,6 × 10-19. Jadi muatan elektron = -1,6 × 10-19 Jadi dari sini kita bisa melihat besar



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muatan elektronik adalah ∣e∣=1,6 × 10-19 C 4. The magnitude of the total negative charge on the electrons in 1 mol of helium (atomic number 2, atomic mass 4) is: A) 4.8  104 C B) 9.6  104 C C) 1.9  105 C D) 3.8  105 C E) 7.7  105 C Ans: C Difficulty: E Nomor elektron dalam satu mol He = 6,023 x 1023 x 2 Muatan pada setiap elektron = 1,6 x 10-19 C Total muatan negatif pada satu mol He = 6,023 x 1023 x 2 x 1,6 x 10-19 = 19,27 x 104 = 1,927 x 105 C 5. The magnitude of the total negative charge on the electrons in 1 kg of helium (atomic number 2, atomic mass 4) is: A) 48 C B) 2.4  107 C C) 4.8  107 C D) 9.6  108 C E) 1.9  108 C Ans: C Difficulty: E Nomer atom He=2 Muatan electron e=1.6x10-19 Q=ne Q=2x1.6x10-19 m=1kg=1000g n=m/M=1000/4=250 N=nL N=2 x 1.6x10-19 x 250 x 6.02 x1023 N=4.8 x107 C 6. A wire contains a steady current of 2 A. The charge that passes a cross section in 2 s is: A) 3.2  10–19 C B) 6.4  10–19 C C) 1 C D) 2 C E) 4 C Ans: E



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Difficulty: E I=2A t= 2 s I = Q/t Q=2x2=4C 7. A wire contains a steady current of 2 A. The number of electrons that pass a cross section in 2 s is: A) 2 B) 4 C) 6.3  1018 D) 1.3  1019 E) 2.5  1019 Ans: E Difficulty: E I=2A t= 2 s muatan electron e = 1.6 x 10-19 C I = Q/t Q=2x2=4C Number of electron (N) = Q/e = 4/ (1.6 x 10-19) = 2.5 x 1019 8. The diagram shows two pairs of heavily charged plastic cubes. Cubes 1 and 2 attract each and cubes 1 and 3 repel each other..



Which



A) B) C) D) E)



of the following illustrates the forces of cube 2 on 3 and cube 3 on 2?



I II III IV V



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Ans: B Difficulty: E Cube 1 dan 2 berbeda muatan sehingga tarik menarik Cube 1 dan 3 muatan sama sehingga tolak menolak Sehingga 2 & 3 memiliki muatan yang sama--- tolak menolak 9. A small object has charge Q. Charge q is removed from it and placed on a second small object. The two objects are placed 1 m apart. For the force that each object exerts on the other to be a maximum. q should be: A) 2Q B) Q C) Q/2 D) Q/4 E) 0 Ans: C Difficulty: M 10. Two small charged objects repel each other with a force F when separated by a distance d. If the charge on each object is reduced to one-fourth of its original value and the distance between them is reduced to d/2 the force becomes: A) F/16 B) F/8 C) F/4 D) F/2 E) F Ans: C Difficulty: M 11. When a piece of paper is held with one face perpendicular to a uniform electric field the flux through it is 25 N  m2/C. When the paper is turned 25 with respect to the field the flux through it is: A) 0 B) 12 N  m2/C C) 21 N  m2/C D) 23 N  m2/C E) 25 N  m2/C Ans: D Difficulty: E Fluks yang melalui medan dapat diperoleh dengan mencari hasil kali titik dari sudut yang kemudian diputar, dan medan listrik seragam yang diberikan. 25 x cos 25 = 22.66, pembulatan= 23 N.m2 /C



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12. The flux of the electric field A) 32 N  m2/C B) 34 N  m2/C C) 42 N  m2/C D) 48 N  m2/C E) 60 N  m2/C Ans: D Difficulty: M 13. Consider Gauss law: A)



through a 2.0 m2 portion of the yz plane is:



Which of the following is true?



must be the electric field due to the enclosed charge



B) If q = 0 then everywhere on the Gaussian surface C) If the three particles inside have charges of +q, +q and 2q, then the integral is zero D) On the surface



is everywhere parallel to



E) If a charge is placed outside the surface, then it cannot affect surface



on the at any point on the



Ans: C Difficulty: E 14. A point charge is placed at the center of a spherical Gaussian surface. The electric flux E is changed if: A) the sphere is replaced by a cube of the same volume B) the sphere is replaced by a cube of one-tenth the volume C) the point charge is moved off center (but still inside the original sphere) D) the point charge is moved to just outside the sphere E) a second point charge is placed just outside the sphere Ans: D Difficulty: E Opsi A dan B tidak benar karena fluks listrik tidak bergantung pada bentuk atau ukuran permukaan, tetapi bergantung pada muatan yang tertutup oleh permukaan. Opsi C juga tidak benar karena muatan masih di dalam permukaan, fluks tidak akan berubah. Opsi E juga tidak benar karena fluks listrik bergantung pada muatan yang dilingkupi permukaan dan tidak bergantung pada muatan di luar bola lain. Namun, opsi D yang benar, karena jika muatan titik dipindahkan dari dalam ke luar bola, fluks akan berubah. 15. Choose the INCORRECT statement: A) Gauss' law can be derived from Coulomb's law B) Gauss' law states that the net number of lines crossing any closed surface in an outward direction is proportional to the net charge enclosed within the surface C) Coulomb's law can be derived from Gauss' law and symmetry D) Gauss' law applies to a closed surface of any shape E) According to Gauss' law, if a closed surface encloses no charge, then the electric field must



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vanish everywhere on the surface Ans: E Difficulty: E 16. The outer surface of the cardboard center of a paper towel roll: A) is a possible Gaussian surface B) cannot be a Gaussian surface because it encloses no charge C) cannot be a Gaussian surface since it is an insulator D) cannot be a Gaussian surface since it is an insulator E) none of the above Ans: D Difficulty: E Untuk hukum Gaussian sesuai dengan setiap permukaan tertutup. Dengan asumsi bahwa paper towel roll tidak tertutup permukaan, opsi terakhir benar: tidak bisa menjadi permukaan Gaussian karena itu bukan permukaan tertutup. 17. A physics instructor in an anteroom charges an electrostatic generator to 25 C, then carries it into the lecture hall. The net electric flux in N  m2/C through the lecture hall walls is: A) 0 B) 25  10–6 C) 2.2  105 D) 2.8  106 E) can't tell unless the lecture hall dimensions are given Ans: D Difficulty: E 18. A point particle with charge q is placed inside a cube but not at its center. The electric flux through any one side of the cube: A) is zero B) is q/0 C) is q/40 D) is q/60 E) cannot be computed using Gauss' law Ans: E Difficulty: E 19. A particle with charge 5.0-C is placed at the corner of a cube. The total electric flux in N  m2/C through all sides of the cube is: A) 0 B) 7.1  104 C) 9.4  104 D) 1.4  105 E) 5.6  105



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Ans: B Difficulty: M 20. A point particle with charge q is at the center of a Gaussian surface in the form of a cube. The electric flux through any one face of the cube is: A) q/0 B) q/40 C) q/40 D) q/80 E) q/160 Ans: D Difficulty: M



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