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Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for AP students and parents). 5 AP® PHYSICS C ELECTRICITY & MAGNETISM
2005 SCORING GUIDELINES
Question 2 (continued)
Distribution
of points
(c) 2 points
After a long time the current is constant, so VL = 0 .
VL = VR2 = 0 , so a constant current goes through resistor 1 and the inductor. Vbatt = VR1
For the correct substitution of both voltage and resistance, using Ohm’s law for VR1 1 point For the correct answer
I batt = e R1 1 point e = I batt R1 (d) 4 points For a graph that rises asymptotically
This point must be earned in order to obtain any of the following points.
For starting the line above zero
For starting the line at the lower limit determined in (a)
For approaching the upper limit determined in part (c)
(e) 1 point
1 point
1 point
1 point 3 points
The current calculated in part (c) that was going through the inductor now goes
through only resistor 2.
For correct application of the loop theorem
I R2 = I L , where I L equals I batt determined in (c) 1 point For correct substitution of both currents, using Ohm’s law for I R2 with a resistance R2 1 point VR2 R2 = e R1 For a correct final answer
VR2 = e R2 R1 1 point Copyright © 2005 by College Entrance Examination Board. All rights reser...
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 Spring '08
 Reich
 Physics, Magnetism

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