PHY 111 College Physics II Spring 2010 Exam 02 Review Name___________________________________ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Two point charges, initially 2.0 cm apart, experience a 1.0-N force. If they are moved to a new separation of 8.0 cm, what is the electric force between them? A) 1/4 N B) 2.0 N C) 4.0 N D) 16 N E) 1/16 N 1) 2) Three point charges are located at the following positions: Q1 = 2.00 μC at x = 1.00 m; Q2 = 3.00 μC at x = 0; Q3 = -5.00 μC at x = -1.00 m. What is the magnitude of the force on the 3.00-μC charge? A) 5.40 × 10-2 N B) 0.158 N C) 8.10 × 10-2 N D) 0.189 N E) 0.135 N 2) 3) A point charge Q = 7.00 × 10-9 C is placed at the origin of an x-y coordinate system. What is the electric field intensity E at a distance of x = 30 cm from this charge? (Use k = 9 × 109 Nm 2/C2.) 3) A) 500 N/C B) 100 N/C C) 700 N/C D) 400 N/C E) 600 N/C 4) A metal sphere of radius 2.0 cm carries a charge of 3.0 μC. What is the electric field 6.0 cm from the center of the sphere? A) 4.2 × 106 N/C B) 9.3 × 106 N/C C) 6.4 × 106 N/C D) 5.7 × 106 N/C E) 7.5 × 106 N/C 4) 5) A proton is placed in an electric field of intensity 700 N/C. What is the magnitude and direction of the acceleration of this proton due to this field? A) 6.71 × 1010 m/s2 opposite to the electric field 5) B) 6.71 × 1010 m/s2 in the direction of the electric field C) 6.71 × 109 m/s2 opposite to the electric field D) 67.1 × 1010 m/s2 in the direction of the electric field E) 67.1 × 1010 m/s2 opposite to the electric field 1 6) An 800 V/m electric field is directed along the +x-axis. If the potential at x = 0 m is 2000 V, what is the potential at x = 2 m? A) 1000 V B) 400 V C) 600 V D) 200 V E) 800 V 6) 7) Three charges are placed as follows along the x- and y-axes of an xy-coordinate system: q1 = 2.00 7) μC at x 1 = 0 m, q2 = 4.00 μC at x 2 = 3.00 m, and q3 = 6.00 μC at y = 4.00 m. What is the electric potential energy of this system of charges? A) -90.0 mJ B) -94.2 mJ C) 0 J D) 94.2 mJ E) 90.0 mJ 8) A 4.0-μC charge is situated at the origin of an xy-coordinate system. What is the potential difference between the points x = 4.0 m and y = 2.0 m because of this charge? A) 0 V B) -9.0 × 103 V 8) C) -36 × 103 V D) 9.0 × 103 V E) 36 × 103 V Figure 20-9 9) Two point charges of magnitude +4.00 μC and +2.00 μC are placed at the opposite corners of a rectangle as shown in Figure 20-9. What is the potential difference between points A and B? A) -203 × 103 V B) -22.5 × 103 V C) +22.5 × 103 V D) 0 V E) +203 × 103 V 2 9) 10) The potential difference between the plates of a parallel plate capacitor is 35 V and the electric field between the plates has a strength of 750 V/m. If the plate area is 4.0 × 10-2 m 2, what is the 10) capacitance of this capacitor? A) 7.6 × 10-14 F B) 7.6 × 10-12 F C) 7.6 × 10-10 F D) 7.6 × 10-11 F E) None of the other choices is correct. 11) A 6.00-μF parallel plate capacitor has a charge of +40.0 μC and -40.0 μC on each plate, respectively. The potential energy stored in this capacitor is: A) 123 μJ B) 133 μJ C) 143 μJ D) 113 μJ E) 103 μJ 11) 12) The resistance of a 100-cm wire of cross sectional area 2 × 10-6 m 2 is 400 Ω. What is the resistivity of the material of this wire? A) 8 × 10-4 Ωm 12) B) 8 × 10-6 Ωm C) 0.8 × 10-6 Ωm D) 0.8 × 10-4 Ωm E) 0.8 × 10-5 Ωm 13) The power rating of a 400 Ω resistor is 0.25 W. What is the maximum voltage? A) 40 V B) 30 V C) 20 V D) 10 V E) 50 V 3 13) Figure 21-3 14) A 4-Ω resistor is connected in parallel with a 12-Ω resistor and this combination is connected to a DC power supply with voltage V as shown in Figure 21-3. If the total current in this circuit is 2 A, what is the value of voltage V? A) 1.5 V B) 2 V C) 3 V D) 6 V E) None of the other answers is correct. 14) Figure 21-7 15) Three 2.0-Ω resistors are connected across the sides of an equilateral triangle ABC as shown in Figure 21-7. What is the equivalent resistance between any two points, AB, BC, or AC, of this circuit? A) 3.3 Ω B) 6.0 Ω C) 1.3 Ω D) 4.3 Ω E) 2.0 Ω 4 15) Figure 21-14 16) A number of resistors are connected across points A and B as shown in Figure 21-14. What is the equivalent resistance between points A and B? A) 6 Ω B) 12 Ω C) 8 Ω D) 10 Ω E) 4 Ω 16) 17) A 2.0 μF and a 4.0 μF capacitor are connected in series across an 8.0-V DC source. What is the charge on the 2.0 μF capacitor? A) 11 μC B) 4.0 μC C) 2.0 μC D) 12 μC E) 25 μC 17) 18) A 8.0 μF capacitor is connected in series with a 6.0 kΩ resistor across a 20-V DC source and a switch. What is the time constant of this RC circuit? A) 12 ms B) 18 ms C) 9.0 ms D) 48 ms E) 40 ms 18) 5 Answer Key Testname: PHY111S10REV02 1) E 2) D 3) C 4) E 5) B 6) B 7) D 8) B 9) B 10) B 11) B 12) A 13) D 14) D 15) C 16) C 17) A 18) D 6

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