Ophthalmic Optics Questions and Answers Flashcards
6 cards from real ABO NOCE Basic Opticianry practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Ophthalmic Optics Questions and Answers flashcards as text
A lens has a power of +3.00 D. What is its focal length?
Answer: 33.3 cm
Focal length (in meters) = 1 / Power. 1 / 3.00 = 0.333 m = 33.3 cm.
Which of the following best describes the index of refraction?
Answer: The ratio of the speed of light in a vacuum to the speed of light in a medium
The index of refraction (n) = speed of light in vacuum / speed of light in medium. Higher index means slower light and greater bending.
Snell's Law states that n1 sin θ1 = n2 sin θ2. If light travels from air (n=1.00) into glass (n=1.50) at an angle of incidence of 30°, what is the angle of refraction?
Answer: 19.47°
1.00 × sin(30°) = 1.50 × sin(θ2). sin(θ2) = 0.5/1.5 = 0.333. θ2 = arcsin(0.333) ≈ 19.47°.
What is the vergence of light at a point 50 cm from a point source?
Answer: -2.00 D
Vergence = 1/distance (in meters). Light from a source is diverging, so vergence = 1/(-0.50 m) = -2.00 D.
A concave mirror has a radius of curvature of 40 cm. What is its focal length?
Answer: 20 cm
For a spherical mirror, focal length = radius of curvature / 2 = 40/2 = 20 cm.
Which type of lens corrects myopia (nearsightedness)?
Answer: Minus (concave) lens
Myopia results from light focusing in front of the retina. A minus (diverging) lens moves the focal point back to the retina.