sign on the d
q
/d
t
term, so 1 point was earned. Part (e)(i) substitutes the correct voltage and resistance into Ohm’s
law, so 2 points were earned. Part (e)(ii) has a concave up curve, indicates that the horizontal axis is an
asymptote, and correctly labels the maximum value, so 3 points were earned. Part (f) has correct selection and
justification, so 2 points were earned.

AP
®
PHYSICS C: ELECTRICITY AND MAGNETISM
2019 SCORING COMMENTARY
© 2019 The College Board.
Visit the College Board on the web: collegeboard.org.
Question 1 (continued)
Sample: E Q1 B
Score: 7
Parts (a), (b), and (c) earned full credit, 2 points each. Part (d) has an incorrect differential equation and an
incorrect sign on the d
q
/d
t
term, so no points were earned. Part (e)(i) does not use the voltage from part (b) and
uses an incorrect resistance in Ohm’s law, so no points were earned. Part (e)(ii) has a concave up curve, but the
horizontal axis is not an asymptote, and the label for maximum value is incorrect, so 1 point was earned. Part (f)
has an incorrect selection and justification, so no points were earned.
Sample: E Q1 C
Score: 3
Part (a) uses Ohm’s law but has an incorrect resistance, so 1 point was earned. Part (b) does not use an
appropriate equation to calculate charge, so no points were earned. Part (c) does not use an appropriate equation
to calculate stored energy, so no points were earned. Part (d) does not use a differential equation, so no points
were earned. Part (e)(i) does not use the voltage from part (b) and uses an incorrect resistance in Ohm’s law, so
no points were earned. Part (e)(ii) has a concave down graph with no horizontal asymptote, and the maximum
voltage is not consistent with part (e)(i), so no points were earned. Part (f) has correct selection and justification,
so 2 points were earned.

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