Exam-style question
Try this first
A student calculates telescope magnification by dividing eyepiece focal length by objective focal length. Which correction should they make?.
- A.Divide the objective focal length by the eyepiece focal length, because angular magnification compares fo with fe in that order.
- B.Add the two focal lengths, because magnification depends on total telescope length.
- C.Multiply both focal lengths, because magnification is a product of lens powers.
- D.Use only the eyepiece focal length, because the objective lens does not affect magnification.
Model answer
What a good answer should say
- The correct option is Divide the objective focal length by the eyepiece focal length, because angular magnification compares fo with fe in that order.
Explanation
Why this works
The other options are incorrect because they invert, add, multiply, or ignore the focal-length relationship for angular magnification in a simple astronomical telescope.
Common mistake
No common mistake is linked to this question yet.