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Unformatted text preview: pan (zp695) Ch23 h2a chiu (56565) 1 This printout should have 20 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 (part 1 of 8) 10.0 points There are a lot of numbers in this problem. Just about the only way to get it right is to work out each step symbolically first, and then plug numbers into the final symbolic result. Two coils of wire are aligned with their axes along the z axis, as shown in the figure below. Coil 1 is connected to a power supply and conventional current flows clockwise through coil 1, as seen from the location of coil 2. Coil 2 is connected to a voltmeter. The distance between the centers of the coils is 0 . 13 m. x y z Coil 1 Coil 2 Voltmeter Power Supply I 1 Coil 1 has N 1 = 530 turns of wire, and its radius is R 1 = 0 . 08 m. The current through coil 1 is changing with time. At t = 0 s, the current through coil 1 is I = 18 A. At t = . 4 s, the current through coil 1 is I 1 = 6 A. Coil 2 has N 2 = 280 turns of wire, and its radius is R 2 = 0 . 03 m. Remember that 4 = 1 10 7 T m / A . Inside coil 2, what is the direction of d B dt during this interval? Choose the unit vector corresponding to this direction. 1. , 1 , 2. , , 1 correct 3. , 1 , 4. 1 , , 5. 1 , , 6. , , 1 Explanation: B 1 at the location of coil 2 is decreasing and is in the z direction. So, d B dt is in the + z direction, and B dt is in the z direction. 002 (part 2 of 8) 10.0 points What is the direction of the electric field inside the wire of coil 2, at a location on the top of coil 2? 1. 1 , , 2. 1 , , correct 3. , 1 , 4. , 1 , 5. , , 1 6. , , 1 Explanation: As viewed from the + x axis, E curls clock wise around coil 2. Thus at the top of the coil, E is in the + x direction. 003 (part 3 of 8) 10.0 points At time t = 0, what is the magnetic flux through one turn of coil? Remember that all turns of coil 1 contribute to the magnetic field. Note that the coils are not very far apart (compared to their radii). Correct answer: 3 . 04977 10 5 T m 2 . Explanation: pan (zp695) Ch23 h2a chiu (56565) 2 = B A cos 0 = 4 2 I 1 A 1 N 1 ( z 2 + R 2 1 ) 3 / 2 A 2 = 4 2(18 A) (0 . 08 m) 2 (530) (0 . 03 m) 2 ((0 . 13 m) 2 + (0 . 08 m) 2 ) 3 / 2 = 3 . 04977 10 5 T m 2 . 004 (part 4 of 8) 10.0 points At t = 0 . 4 s, what is the magnetic flux through one turn of coil 2? Correct answer: 1 . 01659 10 5 T m 2 . Explanation: At t = 0 . 4 s, I 1 = 6 A and = 3 . 04977 10 5 T m 2 . Note that I 1 , so since I 1 = 1 3 I , the magnetic flux decreases by the same factor. So 1 = 1 3 = 1 . 01659 10 5 T m 2 ....
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 Spring '08
 Turner

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