This question-specific review guide is tied to the answer reasoning for a PracticeTestVault item. Use it after you answer the question so the review stays focused on what the prompt actually tested.
What this question is testing
Objective: Ophthalmic optics
Prompt focus: A spectacle lens has a power of plus 5.00 diopters. What is the focal length of this lens?
Why the correct answer works
0.20 meters
The focal length is 1 divided by 5.00 diopters, which equals 0.20 meters.
Why the tempting wrong answer fails
0.50 meters would correspond to a 2.00 diopter lens, not a 5.00 diopter lens.
Plain-language takeaway
The focal length of a lens in meters equals the reciprocal of its power in diopters. Dividing 1 by the dioptric power yields the focal length.
Simple analogy
Think of ophthalmic optics like following a short checklist: identify the clue, confirm the rule, and then make the move that fits this exact scenario.
How to review it before a retake
- Underline the command word and name what the question is asking before rereading the choices.
- Compare the correct answer against the closest distractor and write the exact detail that separates them.
- Retest this objective with a fresh question without looking at the rationale first.