Cuesta College, San Luis Obispo, CA
Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 20.55
[10 points.] An ideal emf source is connected to an ideal resistor and inductor. The switch is closed at t = 0. Determine whether the resistor or inductor has more current flowing through it just after the switch is closed, or if there is a tie. Explain your reasoning using the properties of currents and potential differences, and Kirchhoff's rules, Ohm's law, Faraday's law and/or Lenz's law. Solution and grading rubric:
- p = 10/10:
Correct. Due to Kirchhoff's junction rule applied to this series circuit, both the resistor and the inductor must have the same current flowing through them at any given moment in time. - r = 8/10:
As (p), but argument indirectly, weakly, or only by definition supports the statement to be proven, or has minor inconsistencies or loopholes. - t = 6/10:
Nearly correct, but argument has conceptual errors, or is incomplete. Says different amounts of current, but at least demonstrates an understanding of Lenz's law. - v = 4/10:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. - x = 2/10:
Implementation/application of ideas, but credit given for effort rather than merit. - y = 1/10:
Irrelevant discussion/effectively blank. - z = 0/10:
Blank.
Grading distribution:
Section 30882
Exam code: midterm02H3nR
p: 3 students
r: 0 students
t: 3 students
v: 2 students
x: 0 students
y: 0 students
z: 0 students
A sample "p" response (from student 7673):
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