ABO NOCE Basic Opticianry Ophthalmic Optics Questions and Answers 2

Question 1

A lens has a power of +3.00 D. What is its focal length?

Accepted Answer

33.3 cm

Answer

Focal length (in meters) = 1 / Power. 1 / 3.00 = 0.333 m = 33.3 cm.

Question 2

Which of the following best describes the index of refraction?

Accepted Answer

The ratio of the speed of light in a vacuum to the speed of light in a medium

Answer

The index of refraction (n) = speed of light in vacuum / speed of light in medium. Higher index means slower light and greater bending.

Question 3

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?

Accepted Answer

19.47°

Answer

1.00 × sin(30°) = 1.50 × sin(θ2). sin(θ2) = 0.5/1.5 = 0.333. θ2 = arcsin(0.333) ≈ 19.47°.

Question 4

What is the vergence of light at a point 50 cm from a point source?

Accepted Answer

-2.00 D

Answer

Vergence = 1/distance (in meters). Light from a source is diverging, so vergence = 1/(-0.50 m) = -2.00 D.

Question 5

A concave mirror has a radius of curvature of 40 cm. What is its focal length?

Accepted Answer

20 cm

Answer

For a spherical mirror, focal length = radius of curvature / 2 = 40/2 = 20 cm.

ABO NOCE Basic Opticianry Practice Test

ABO NOCE Basic Opticianry Practice Test

ABO NOCE Basic Opticianry Ophthalmic Optics Questions and Answers 2