Cuesta College, San Luis Obispo, CA
Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Multiple-Choice Question 24.3
[10 points.] A Physics 205B student cannot see distant objects, but can still see nearby objects. Would this student require a diverging lens or a converging lens prescription for a pair of glasses? Explain your reasoning using the properties of lenses and corrective optics.
Solution and grading rubric:
- p = 10/10:
Correct. A diverging lens would be required, whether arguing from the intermediate (virtual) image created by the lens being closer to the eye than the original object, such that the eye would be able to see it; and/or a diverging lens will diverge the rays such that the image produced in front of a retina for myopia will then converge further back, onto the retina. - 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. Recognizes that a lens that would create an image closer than the original object is required, but chooses a converging lens. - v = 4/10:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Choice of lens motivated by magnification. - 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 31988
p: 5 students
r: 0 students
t: 4 students
v: 4 students
x: 0 students
y: 0 students
z: 0 students
A sample "p" response (from student 1930):
Another sample "p" response (from student 7575):
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