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Name: PES 112 General Physics II Practice Exam 1 • • • Show all work. Attach additional paper if needed. If you disagree with all of the available answers, indicate your solution. Provide units where indicated with ( ). One (3” x 5”) index card may be used for formulas or other notes or diagrams. Definitions & Concepts (2 pts each) 1. Equipotentials are lines along which: a. The electric field is constant in magnitude and direction. b. The electric charge is constant in magnitude and direction. c. A charge moving at constant speed requires the maximum amount of work to be done against electrical forces. d. A charge may be moved at constant speed without work against electrical forces e. Charges move by themselves. 2. The electric potential inside a charged solid spherical conductor in equilibrium: a. Is always zero. b. Is constant and equal to its value at the surface. c. Decreases from its value at the surface to a value of zero at the center. d. Increases from its value at the surface to a value at the center that is a multiple of the potential at the surface. e. Is equal to the charge passing through the surface per unit time divided by the resistance. 3. What units will result from the multiplication of volts times coulombs? a. Newtons b. Meters per second c. Kilograms per meter d. Joules Applications (4-6 pts each) 4. If a = 3.0 mm, b = 4.0 mm, Q1 = –60 nC, Q2 = 80 nC, and q = 30 nC in the figure, what is the magnitude of the total electric force on q? 5. If a = 60 cm, b = 80 cm, Q = –6.0 nC, and q = 6.0 nC, what is the magnitude of the electric field at point P in the figure? R. Gist 1 of 3 Long Semester Ver. B, Rev 1 PES 112 General Physics II Practice Exam 1 6. An electron enters a region of uniform electric field (E = 50 N/C) with an initial velocity of 40 km/s directed the same as the electric field. What is the speed of the electron 1.5 ns after entering this region? 7. The total electric flux through a closed cylindrical (length = 1.2 m, diameter = 0.20 m) surface is equal to —5.0 N ⋅ m2/C. Determine the net charge within the cylinder. 8. Charge of a uniform density (8.0 nC/m2) is distributed over the entire xy plane. A point charge of 5.0 μC is fixed at z = 1.0 m. Determine both the magnitude of the electric field and the electric potential for the point midway between the point and the plane. 9. What amount of charge can be placed on a spherical conductor with radius = 1.0 cm, before arc discharge will occur due to dielectric breakdown of the air? 10. A spherical conductor of radius 5 cm has 6 μC of charge placed on it. A smaller, neutrally charged conducting sphere of radius 3 cm is attached via a long, thin wire far from the first sphere. How much charge moves from the large sphere to the small one? R. Gist 2 of 3 Long Semester Ver. B, Rev 1 PES 112 General Physics II Practice Exam 1 11. Three identical point charges (+2.0 nC) are placed at the corners of an equilateral triangle with sides of 2.0-m length. If the electric potential is taken to be zero at infinity, what is the electric potential at the midpoint of any one of the sides of the triangle? What is the potential energy contained in this system due to the three charges? Types of charged objects that may be used on the exam: Uniformly charged object shape Infinite line of charge with linear charge density λ Electric field Electric Potential Infinite plane of charge with surface charge density σ Point of charge q Spherical shell of charge with surface charge density σ Sphere of solid charge with charge density ρ R. Gist 3 of 3 Long Semester Ver. B, Rev 1