Cuesta College, San Luis Obispo, CA
[20 points.] An astronomy question on an online discussion board(*) was asked and answered:
ahriik: What is a good telescope for a beginner? I want to get into astronomy, so I believe a telescope is essential.Discuss reasons why "there's not much point in investing" in a small diameter telescope. Support your answer using the properties of telescope parameters and telescope powers.
eri:[F]or a good beginner telescope; the most important factor is the size of the primary mirror... There's not much point in investing in a telescope if the primary mirror diameter is less than 4.5", and the bigger the better...
Solution and grading rubric:
- p = 20/20:
Correct. Discusses how diameter of primary lens/mirror determines the light-gathering power and resolving power, such that a large diameter lens/mirror would result in bright, finely resolved images worth magnifying.
- r = 16/20:
Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. Discusses how diameter affects either light-gathering power or resolving power, other diameter/power discussion incomplete.
- t = 12/20:
Contains right ideas, but discussion is unclear/incomplete or contains major errors. Problematic discussion of how diameter is related to either light-gathering power or resolving power.
- v = 8/20:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. At least discusses some connection between telescope parameters and telescope power.
- x = 4/20:
Implementation/application of ideas, but credit given for effort rather than merit. Does not discuss connection between telescope parameters and telescope powers.
- y = 2/20:
Irrelevant discussion/effectively blank.
- z = 0/20:
Exam code: midterm01neE7
p: 18 students
r: 14 students
t: 0 students
v: 1 student
x: 0 students
y: 0 students
z: 0 students
Exam code: midterm01s0Be
p: 21 students
r: 15 students
t: 1 student
v: 3 students
x: 1 student
y: 1 student
z: 0 students
A sample "p" response (from student 4490):
Another sample "p" response (from student 0010):