Cuesta College, San Luis Obispo, CA
Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Conceptual Question 18.22.
Consider an ideal 16.0 V emf source connected to a 15 Ω resistor, two ideal ammeters, and two 2.2 Ω light bulbs, as shown at right. If the 15 Ω resistor were replaced with an ideal wire (and everything else were unchanged), the brightness of light bulb 1 would:(A) increase.
(B) remain the same.
(C) decrease, but will still be lit.
(D) be completely dead.
Correct answer: (D)
Since there would now be a zero resistance path in parallel with light bulb 1, then the current through light bulb 2 at the junction would all go through this branch in the circuit, and none would go through light bulb 1, which is now effectively "shorted out."
Student responses
Section 30822
Exam code: quiz05t4Uo
(A) : 0 students
(B) : 3 students
(C) : 3 students
(D) : 2 students
Success level: 25%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.50
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