American Board of Ophthalmology (ABO) Practice Exam

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Prepare for the American Board of Ophthalmology Exam. Study with interactive quizzes and comprehensive explanations to ensure you pass your test with confidence. Dive into a balanced mix of detailed questions and helpful hints for a successful exam experience.

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Which substance has the lowest index of refraction?

Water
Glass
Diamond
Air

The correct answer is: Air

The index of refraction is a measure of how much a substance bends light compared to a vacuum. Air, being a gas, has an index of refraction close to 1.0003, which is lower than those of water, glass, and diamond. Water typically has an index of refraction around 1.33, glass ranges from about 1.5 to 1.9 depending on its composition, and diamond possesses a notably high index of refraction, approximately 2.42. Therefore, air has the lowest index of refraction among the substances listed. The significance of this characteristic is crucial in optics. Lower indices of refraction indicate that the substance deflects light less than substances with higher indices, which is fundamental in understanding the behavior of light as it passes through different media.