2008PracticeExam3

# 2008PracticeExam3 - Name: _ Code # _ Summer Session, 2008...

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Name: ________________________________________ Code # _________ Summer Session, 2008 ID: X 1 UCSD Physics 2B Practice Exam 3 Current & Resistance READ ME !!! Helpful Hints: Do this exam a few times. .. Once without the answers, Once after seeing the solutions & Once again with your formula sheet This is a good time to add formulas/constants to your sheet. Remember, this is a timed exam. .. work swiftly so you have time to check your answers. 1. A heating coil operates at 117 V. If it draws 10.5 Amps of current, find its resistance . A. 128 Ω B. 8.97 × 10 2 Ω C. 1.23 × 3 Ω D. 11.1 Ω 2. Two lamps each of resistance R = 10.0 Ω are connected in series to voltage source V = 120 V as shown in the diagram below. What is the current through each lamp? A. 6.00 A B. 12.0k A C. 130 A D. 83m A

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Name: ________________________ ID: A 2 3. Find the equivalent resistance of the network shown below if R 1 = 25.0 Ω and R 2 = 17.3 Ω A. 42.3 Ω B. 9.71 m Ω C. 10.2 Ω D. 7.70 Ω 4. Find the power dissipated by resistor R 1 in the circuit shown below if V = 50 V , R 1 = 25.0 Ω and R 2 = 17.2 Ω . A. 145 W B. 59.2 W C. 100 W D. 2.91 W 5. It takes 6.75 seconds for a capacitor to be “charged” with 175 Coulombs. What average current flows into the capacitor during this time? A. 25.9 A B. 38.6 mA C. 25.9 mA D. 38.6 A
Name: ________________________ ID: A 3 6. If 4.70 × 10 16 electrons pass a particular point in a wire every second, what current flows through the wire? A. 7.52 mA B. 133 mA C. 7.52 A D. 133 A 7. How much electric energy (in Joules) is delivered in 5.00 minutes to an electric motor that draws 0.500 Amps from a 6.00 Volt battery? A. 900 J B. 15 J C. 60 J D. 54 kJ 8. Find the current through resistor R 2 in the circuit diagram below if R 1 = R 2 = R 3 = 30.0 Ω and V = 75.0 Volts R 1 V R 2 R 3 A. 833 mA B. 400 mA C. 2.50 A D. 1.67 A

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Name: ________________________ ID: A 4 9. A bicycle wheel of radius 15 inches is given an electric charge Q = 750 mC which is distributed evenly over the surface of the tire as shown below. If the wheel is set spinning at 120 rpm, what is the electric current that a stationary observer at the rim would measure? A. 1.50 A B. 90.0 A C. 12.5 mA D. 667 mA 10. In the circuit below, R 1 = 11.5 Ω , R 2 = 16.5 Ω , and R 3 = 22.3 Ω . If the current through the circuit is 1.34 A, what is the voltage of the battery? A. 67.4 V B. 1.74 V C. 32.3 V D. 50.3 V
Name: ________________________ ID: A 5 11. If 4.0 x 10 18 electrons and 1.5 x 10 18 protons move in opposite directions past a given section of a hydrogen discharge tube every second, the average current in the tube is A. 0.40 A B. 0.56 A C. 0.88 A D. 1.5 A 12. Wire A, which is of the same length and material as wire B, has twice the cross-sectional area of wire B. If the resistance of wire B is R B , what is the resistance R A of wire A? A. R B / 4 B. 2 R B C. R B / 2 D. 4 R B 13. If electric energy costs 10 cents per kilowatt-hour (you wish!), how many cents does it cost to keep a 660-W toaster in steady operation for 30 minutes?

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## This note was uploaded on 08/23/2008 for the course PHYS 2b taught by Professor Schuller during the Summer '08 term at UCSD.

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2008PracticeExam3 - Name: _ Code # _ Summer Session, 2008...

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