American Board of Opticianry (ABO) Practice Test

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Prepare for the ABO (American Board of Opticianry) Test with interactive flashcards and hundreds of multiple choice questions. Updated for 2024 to help you excel on exam day

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

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What is the focal length of a +4.00 diopter lens?

15 cm
25 cm
35 cm
45 cm

The correct answer is: 25 cm

The focal length of a +4.00 diopter lens is 25 cm. Diopters are a unit of measurement used to describe the optical power of a lens, and they are equal to the reciprocal of the focal length measured in meters. As the diopter value increases, the focal length decreases, resulting in a more strongly converging lens. Therefore, options A, C, and D are incorrect because they have larger focal lengths and lower diopter values. In contrast, option B has a smaller focal length and a higher diopter value, making it the correct answer.