Physics quiz question: contact-shorted battery

Physics 205B Quiz 5, spring semester 2010
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 18.95(a)

"20100220488"
Waifer X
flic.kr/p/7EusJt

A Physics 205B student accidentally touches the terminals of an ideal battery with an emf of 67.5 V, and experiences a tingling sensation from 0.50 mA of current. The resistance of the student is:
(A) 34 Ω.
(B) 1.4×10² Ω.
(C) 3.4×10⁴ Ω.
(D) 1.4×10⁵ Ω.

Correct answer (highlight to unhide): (D)

From Ohm's law,

I = ΔV/R,

such that solving for R,

R = ΔV/I = (67.5 V)/(0.50×10^–3 A) = 1.35×10⁵ Ω,

or 1.4×10⁵ Ω, to two significant figures.

Section 31988
Exam code: quiz04v0L7
(A) : 1 student
(B) : 1 student
(C) : 1 student
(D) : 7 students

Success level: 70%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.25