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Unformatted text preview: pan (zp695) – ch24-h1 – chiu – (56565) 1 This print-out should have 15 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 (part 1 of 3) 10.0 points N closely spaced turns of wire are wound in the direction indicated on a hollow, plastic ring of radius R , with circular cross section, as in the figure below. R I I If the current in the wire is I , determine the magnetic field B at the location indicated by the × , at the center of the cross section of the ring. 1. B = μ 4 π 2 N I R correct 2. B = μ 4 π N I R 3. B = μ π N I R 4. B = μ π N I R 2 5. B = μ 4 π 2 N I R 2 Explanation: Use Ampere’s Law with a circular loop C of radius R along the toroid’s midline. C B · d = μ I 2 π R B = μ N I ⇒ B = μ 4 π 2 N I R . 002 (part 2 of 3) 10.0 points Which of the following arrows best indicates the direction of the magnetic field at the × ? I II III IV V VI VII VIII 1. V 2. I 3. II 4. IV 5. VII 6. VIII correct 7. VI 8. III Explanation: Knowing which way the current is moving through the wire, we can use the right hand rule to determine that the magnetic field is going clockwise through the cross section of the ring, meaning that at the × it is directed toward the upper-left, or arrow VIII. 003 (part 3 of 3) 10.0 points Throughout this region there is a uniform electric field E into the paper. This electric field begins to increase at a rate dE/dt , and there continues to be a current I in the wire. Now what is the magnitude of the magnetic field at the indicated point? 1. B = μ 4 π 2 N I R + R 2 2 π c 2 d E dt pan (zp695) – ch24-h1 – chiu – (56565) 2 2. B = μ 4 π 2 N I R + R 2 c 2 d E dt correct 3. B = μ 4 π 2 N I R 2 + R 2 π c 2 d E dt 4. B = μ π N I R + R 2 4 c 2 d E dt 5. B = μ 4 π N I R + R 2 c 2 d E dt Explanation: Use Ampere’s law, as modified by Maxwell,...
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- Spring '08
- Magnetic Field, 5 m, 10 m, 0 m, 8 m/s, 108 m/s