Physics quiz question: induced emf in inductor

Physics 205B Quiz 6, spring semester 2012
Cuesta College, San Luis Obispo, CA

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

An ideal emf source is connected to an ideal resistor and inductor. The switch is closed at t = 0. Just after t = 0, the __________ side 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)

Just after the switch is thrown at t = 0, increasing current will flow through the inductor from right-to-left. The resulting induced emf in the inductor will oppose this increasing current, resulting in the right side of the inductor being at a higher potential.

Section 30882
Exam code: quiz06LR1r
(A) : 10 students
(B) : 15 students
(C) : 2 students
(D) : 0 students

Success level: 56%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.58