862_Physics ProblemsTechnical Physics

862_Physics ProblemsTechnical Physics - 202 Sources of the...

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202 Sources of the Magnetic Field Additional Problems P30.48 B IR RR I R = + = µµ 0 2 22 32 0 52 2 2 ej I BR == ×× ×⋅ 2 2 7 00 10 6 37 10 41 0 0 5 6 7 µ π .. T m TmA so I 201 10 9 . A toward the west P30.49 Consider a longitudinal filament of the strip of width dr as shown in the sketch. The contribution to the field at point P due to the current dI in the element dr is dB dI r = 0 2 where dI I dr w = F H G I K J BB k k = + F H G I K J zz + d Idr wr I w w b b bw 00 1 ± ln ± . FIG. P30.49 P30.50 Suppose you have two 100-W headlights running from a 12-V battery, with the whole 200 17 W 12 V = A current going through the switch 60 cm from the compass. Suppose the dashboard contains little iron, so 0 . Model the current as straight. Then, B I r × 0 7 5 2 01 7 20 6 10 a f . ~ T . If the local geomagnetic field is 5 10 5 × T, this is ~10 1 times as large, enough to affect the compass noticeably.
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This note was uploaded on 12/14/2011 for the course PHY 203 taught by Professor Staff during the Fall '11 term at Indiana State University .

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