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Unformatted text preview: Exam II Solutions Part A. Multiple choice questions. Check the best answer. Each question carries a value of 4 points. 1. Concerning lines of the electromagnetic Felds: No E-Feld lines form closed curves and all B-Feld lines do. All Feld lines of both Felds form closed curves. √ Some E-Feld lines form closed curves and all B-Feld lines do. Some lines of both Felds form closed curves, and some do not. 2. Midway between the two long parallel wires shown is a positive point charge moving with velocity v , parallel to the wires. The current in the upper wire is I , to the right. Which of the following is wrong? If the current in the lower wire is also I to the right the charge continues to move to the right at constant velocity. [Total Feld is zero.] √ If the current in the lower wire is I to the left the charge will curve toward the lower wire. [Upper wire.] If the current in the lower wire is zero the charge will curve toward the upper wire. If the current in the lower wire is 2 I to the right, the charge will curve toward the lower wire. I q v Physics 54 Summer 2010 1 3. Two identical bar magnets, A and B, are dropped from rest from the same height, oriented vertically so that one pole is above the other. Magnet A is dropped onto a wooden surface, while magnet B is dropped onto a copper plate. The one that lands Frst is: √ Magnet A. [No retardation from eddy currents.] Magnet B. They land at the same time. Whichever has its north pole downward. 4. Shown is an inductor and a resistor as part of a circuit. The current shown is increasing. The terminal voltage V b − V a is positive. [Negative.] The inductor is supplying energy to the circuit. [See below.] √ Both elements are taking energy out of the circuit. [Energy is going into the magnetic Feld of the inductor, and into heat in the resistor.] None of the above is true....
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This note was uploaded on 10/19/2011 for the course PHYSICS 54L taught by Professor Thomas during the Summer '09 term at Duke.
- Summer '09