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Unformatted text preview: apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for AP students and parents). 7 AP® PHYSICS C ELECTRICITY & MAGNETISM
2005 SCORING GUIDELINES
Question 3 (continued)
Distribution
of points
(c) 6 points BS = m0 nI
For correctly relating the slope of the graph to m0 I 1 point DBS
Dn
For correctly finding the slope
For using at least one point from the graph in the calculation (i.e., not using two points
from the chart that are not on the bestfit line)
From the graph shown here
9.5 ¥ 10 4  4.5 ¥ 10 4 T
DBS
5.0 ¥ 10 4 T
=
=
130 turns m
Dn
(240  110) turns m
m0 I = slope of line = ( 1 point ) For correctly substituting the obtained slope into the equation for m0
For correctly substituting the given value of I
1
5.0 ¥ 10 4 T
m0 ex =
3.0 A 130 turns m m0 ex = 1.3 ¥ 10 6 ( Tim ) A
For the correct units (d) 1 point 1 point
1 point 1 point 2 points
For a correct percent error formula
m  m0 ex
percent error = 0
(100 )
m0 1 point For using the value of m0 ex from part (c) 1 point percent error = 4 p ¥ 10 7 (T im ) A  1.3 ¥ 10 6 (T im ) A 4 p ¥ 10 7 (T im ) A
percent error = 0.035 (100 )
percent error = 3.5% (100) Copyright © 2005 by College Entrance Examination Board. All rights reserved.
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This note was uploaded on 08/05/2009 for the course PHYS 101 taught by Professor Reich during the Spring '08 term at Johns Hopkins.
 Spring '08
 Reich
 Physics, Magnetism

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