Physics quiz question: self-inductance

Physics 205B Quiz 6, Fall Semester 2010
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 20.55.

The current passing through an ideal inductor L is increasing over time. The __________ end of the inductor is at a higher potential.
(A) left.
(B) right.
(C) (There is a tie.)
(D) (Not enough information is given.)

Correct answer: (B)

From Lenz's law, the inductor will have a back emf induced in it that will fight the increasing current flowing to the left, resulting in the right end being at a higher potential (with the left end at a lower potential), corresponding to an induced current that points to the right, opposite the direction of the increasing external current.

Student responses
Section 70856
(A) : 5 students
(B) : 6 students
(C) : 0 students
(D) : 0 students

Success level: 54%
Discrimination index (Aubrecht & Aubrecht, 1983): 1.00

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