EF 152 Exam 2 (E&M) - Spring, 2018 Page 1 Version: A Copy 480 Name: Section: Seat Assignment: Specify your EXAM ID on the right. Use 000 if you do not know your exam ID. 0 0 0 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 6 6 6 7 7 7 8 8 8 9 9 9 Instructions Do not open the exam until instructed to do so. Do not leave if there is less than 5 minutes to go in the exam. When time is called, immediately stop writing, remain seated, and pass your exam to the center aisle. Working after time is called results in an automatic deduction. Turn your equation sheets in with your exam. Guidelines Assume 3 significant figures for all given numbers unless otherwise stated Show all of your work no work, no credit Write your final answer in the box provided Include units for all answers
EF 152 Exam 2 (E&M) - Spring, 2018 Page 2 Version: A Copy 480 1. (2 pt) A positively charged particle is located at the origin of a standard coordinate system. What is the direction of the electric field vector at the location <0,5,0> m? 2. (2 pt) A positively charged particle is located at the origin of a standard coordinate system and moving with a velocity of <0,10,0> m/s. What is the direction of the magnetic field vector at the location <5,0,0> m? 3. (2 pt) A positively charged particle is located at the origin of a standard coordinate system and is subjected to an electric field of <5,0,0> N/m. What is the direction of the force on the particle? 4. (2 pt) A positively charged particle is located at the origin of a standard coordinate system and moving with a velocity of <0,10,0> m/s through a magnetic field of <0,0,5> Gauss. What is the direction of the magnetic field force on the particle? 5. (2 pt) How much power is dissipated by a 2 Ω resistor carrying a current of 3A 6 W 12 W 18 W 6 V 12 V 18 V 6. (2 pt) Two charges, Q 1 = 5 C and Q 2 = 1 C, exert a force on each other due to their charges. F 1 is the force on Q 1, and F 2 is the force on Q 2. How does the magnitude of the forces compare? F1 < F2 F1 = F2 F1 > F2 7. (2 pt) Which is NOT a valid unit for resistance? Ω A 2 /W V/A W/A 2
EF 152 Exam 2 (E&M) - Spring, 2018 Page 3 Version: A Copy 480 8. (2 pt) How is a resistor s value shown on the component itself? Text Bar code Color bands It isn t labeled 9. (2 pt) What voltage was used for circuits on the breadboard in the Arduino lab? 5 V 10 V 12 V 120 V 10. (2 pt) In Kirchoff s laws, which is true of any closed loop? ƩI = 0 ƩV = 0 ƩR = 0 ƩP = 0 11. (5 pt) A circuit uses 1.2 m of copper wire (ρ= 1.72x10-8 Ω -m). The resistance of the circuit is 0.61 ohm. What is the diameter of the wire? 12. (5 pt) What is the cost to have 100 W light bulb turned on for 8 hours if energy costs $0.09 per kw-hr?
EF 152 Exam 2 (E&M) - Spring, 2018 Page 4 Version: A Copy 480 13. (5 pt) Two electricians each have a charge of 5.0 nc and experience a 31 nn force due to their charge. How far are they apart? 14. (5 pt) What is magnitude of the electric field at point A due to the two charges shown. A 30 30-2 nc +2 nc 15. (5 pt) What is the equivalent resistance between A and B for this set of resistors?
EF 152 Exam 2 (E&M) - Spring, 2018 Page 5 Version: A Copy 480 16. (13 pt) Determine voltage E2 for this circuit. 17. (14 pt) A long piece of copper has a resistance of 2.3 Ω at 20 C. The same piece of copper is cooled to -150 C and then subjected to a current of 8100 A for 53 milliseconds. How much energy is absorbed by the wire? Copper: α = 0.00404/ C ρ = 1.72 x 10-8 Ω-m
EF 152 Exam 2 (E&M) - Spring, 2018 Page 6 Version: A Copy 480 18. (14 pt) Find the magnetic field (i, j, k notation) at the origin. Q 2:+3nC Q 1:+7 nc 0.25m 6000 m/s 2000 m/s 0.42m y x 19. (14 pt) An electron (1.602x10-19 C, 9.109x10-31 kg) starts with a velocity of <4200, 0, 0> m/s. After 0.003 seconds of moving through a constant electric field it has a velocity of <4200, 2200, 0> m/s. What is the magnitude of the electric field? (neglect gravity)