20_InstSolManual_PDF_Part10 - feasible(b The magnetic force...

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20.29. Set Up: The direction of is determined by applying the right-hand rule to the directions of I and Solve: (a) The directions of I and are sketched in Figure 20.29a. and The right-hand rule says that is directed out of the page, so is upward. Figure 20.29 (b) The directions of I and are sketched in Figure 20.29b. and is directed east to west. (c) and the direction of the current are antiparallel. and (d) The magnetic force of is not large enough to cause significant effects. Reflect: The magnetic force is a maximum when the directions of I and are perpendicular and it is zero when the current and magnetic field are either parallel or antiparallel. 20.30. Set Up: The magnetic force is and is maximum when For the wire to be completely supported by the field requires that and that and are in opposite directions. Solve: (a) This is a very large current and ohmic heating due to the resistance of the wire would be severe; such a current isn’t
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Unformatted text preview: feasible. (b) The magnetic force must be upward. The directions of I, and are shown in Figure 20.30, where we have assumed that is south to north. To produce an upward magnetic force, the current must be to the east. The wire must be horizontal and perpendicular to the earth’s magnetic field. Figure 20.30 E N S W F I B B S F S B S I 5 mg lB 5 1 0.150 kg 21 9.80 m / s 2 2 1 2.00 m 21 0.55 3 10 2 4 T 2 5 1.34 3 10 4 A. IlB 5 mg . w S F S F 5 mg f 5 90°. F 5 IlB sin f B S 2.1 3 10 2 4 N F 5 0. f 5 180° B S F S F 5 2.1 3 10 2 4 N. f 5 90° B S E N S W F I B ( a ) E N S W F I B ( b ) F S F 5 1 1.5 A 21 2.5 m 21 0.55 3 10 2 4 T 2 5 2.1 3 10 2 4 N. f 5 90° B S 1 gauss 5 10 2 4 T. B S . F S F 5 IlB sin f . 20-10 Chapter 20...
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This note was uploaded on 03/06/2009 for the course PHYS 114 taught by Professor Shoberg during the Spring '07 term at Pittsburg State Uiversity.

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