COT Clinical Optics UPDATED Actual
Exam Questions and CORRECT Answers
Focal Length - CORRECT ANSWER✔✔- F.L. = 1 / Diopter
Diopter = 1 / F.L (meters)
Prism - CORRECT ANSWER✔✔- Δ = Diopter / Meters
Diopters = Δ * Meters
Meters = Diopters / Δ
Prentices Rule - CORRECT ANSWER✔✔- Δ = (Diopters * decentration (mm)) / 10
Diopters = (Δ * 10) / dec (mm)
dec (mm) = (Δ * 10) / Diopters
Radius of Curvature (Contact Lens) - CORRECT ANSWER✔✔- Radius of Curvature (mm)
= 337.5 / (K Reading in Diopters)
K Reading in Diopters = 337.5 / (Radius of Curvature in mm)
Radius of Curvature - CORRECT ANSWER✔✔- Radius of Curvature = (n - 1) / Diopters
Diopters = (n - 1) / R
Prismatic Power - CORRECT ANSWER✔✔- Δ = deviation (cm) / distance away (Meters)
Δ = a (n -1)
a = apical angle
Snells Law - CORRECT ANSWER✔✔- n = sin(θi) / sin(θr)
Vergence - CORRECT ANSWER✔✔- V = U + F
V = 100 / v vergence of image (to the right of the lens/mirror in diopters)
U = 100 / u vergence of object (to the left of the lens/mirror in diopters)
,F = 100 / f diopter value of lens or mirror
v = 100 / V distance to the right (left for mirror) where the image forms (cm)
u = 100 / U distance to the left where the object is (cm)
f = 100 / F focal point of lens or mirror (cm)
Back Vertex Power: (Ocular surface toward lens stop) - CORRECT ANSWER✔✔-
Dioptereffective power = Diopterfront + Diopterback + (ThicknessMeters * (Diopterfront)2) /
n
Front Vertex Power: (Objective surface toward lens stop) - CORRECT ANSWER✔✔-
Dioptereffective power = Diopterfront + Diopterback + (ThicknessMeters * (Diopterback)2) /
n
Immediately on either side of the visible spectrum are the invisible light segments of:
a) Infrared and ultraviolet
b) X-rays and radio waves
c) Gamma rays and laser
d) Microwaves and radar - CORRECT ANSWER✔✔- a) Infrared light borders the visible
color red and ultraviolet light borders the visible color violet. All of the other answers are
invisible components of the electromagnetic spectrum, but do not abut red or violet.
Which color has the longest wavelength?
a) Red
b) Yellow
c) Green
d) Blue - CORRECT ANSWER✔✔- a) Red has the longest wavelength: 650 nanometers.
Geometric optics includes:
a) The origin of light waves and particles
b) The effects of media on the path of light
c) How light travels through the eye
,d) Physics of the visible light spectrum - CORRECT ANSWER✔✔- b) Geometric optics
involves the reaction of light as it passes through media (any transparent object) or strikes a
surface. Answers a and d refer to physical optics. Physiologic optics defines answer c.
When light bounces back from an object, this is known as:
a) Reflection
b) Refraction
c) Transmission
d) Index of refraction - CORRECT ANSWER✔✔- a) When light strikes an object or an
interface between media with different indices of refraction and bounces back, this is called
reflection.
In reflection, the light rays that hit the object or interface between media with different
indices of refraction are called:
a) Incident rays
b) Reflected rays
c) Refracted rays
d) Transmitted rays - CORRECT ANSWER✔✔- a) The light that hits the object or interface
is termed incident. Those rays that bounce back from the object or interface are called
reflected.
In optics, a medium (or media, plural) is:
a) An object that refracts light
b) An object that emits light
c) An object that reflects light
d) An object through which light passes - CORRECT ANSWER✔✔- d) A medium is a
transparent object through which light can pass. It is not a light source (ie, does not emit
light). It does not necessarily refract light, either (see next question).
When light passes through a transparent medium, it may travel straight through
(Transmission or its path may be altered. This altering or bending property of a medium is
known as:
a) Reflection
b) Refraction
, c) Absorption
d) Tropism - CORRECT ANSWER✔✔- b) The quality of a medium to bend light is called
refraction. In reflection, the rays are bounced off of the surface. Absorbed light does not pass
through a medium. Tropism actually refers to the phenomenon of plants bending toward a
light source.
The ray of light that enters a transparent medium is termed:
a) Incident ray
b) Divergent ray
c) Emergent ray
d) Parallel ray - CORRECT ANSWER✔✔- a) The incident ray is the ray that first strikes and
enters a medium. A divergent ray has been refracted outward. The emergent ray is the ray as
it exits the medium. A parallel ray is straight.
If light passes through a lens and the rays are spread apart on exiting, this is known as:
a) a) Index of refraction (IR)
b) Convergence
c) Zero vergence
d) Divergence - CORRECT ANSWER✔✔- d) If the light is spread apart by the lens, the rays
are said to be divergent.
If light passes through a lens and the rays are bent toward each other on exiting, this is known
as:
a) IR
b) Convergence
c) Zero vergence
d) Divergence - CORRECT ANSWER✔✔- b) Convergence occurs when light rays are
brought together (bent inward) by the lens.
A comparison of the speed of light in air to the speed of light through a substance is:
a) IR (Snell's Law)
b) Angle of refraction
c) Internal reflection
Exam Questions and CORRECT Answers
Focal Length - CORRECT ANSWER✔✔- F.L. = 1 / Diopter
Diopter = 1 / F.L (meters)
Prism - CORRECT ANSWER✔✔- Δ = Diopter / Meters
Diopters = Δ * Meters
Meters = Diopters / Δ
Prentices Rule - CORRECT ANSWER✔✔- Δ = (Diopters * decentration (mm)) / 10
Diopters = (Δ * 10) / dec (mm)
dec (mm) = (Δ * 10) / Diopters
Radius of Curvature (Contact Lens) - CORRECT ANSWER✔✔- Radius of Curvature (mm)
= 337.5 / (K Reading in Diopters)
K Reading in Diopters = 337.5 / (Radius of Curvature in mm)
Radius of Curvature - CORRECT ANSWER✔✔- Radius of Curvature = (n - 1) / Diopters
Diopters = (n - 1) / R
Prismatic Power - CORRECT ANSWER✔✔- Δ = deviation (cm) / distance away (Meters)
Δ = a (n -1)
a = apical angle
Snells Law - CORRECT ANSWER✔✔- n = sin(θi) / sin(θr)
Vergence - CORRECT ANSWER✔✔- V = U + F
V = 100 / v vergence of image (to the right of the lens/mirror in diopters)
U = 100 / u vergence of object (to the left of the lens/mirror in diopters)
,F = 100 / f diopter value of lens or mirror
v = 100 / V distance to the right (left for mirror) where the image forms (cm)
u = 100 / U distance to the left where the object is (cm)
f = 100 / F focal point of lens or mirror (cm)
Back Vertex Power: (Ocular surface toward lens stop) - CORRECT ANSWER✔✔-
Dioptereffective power = Diopterfront + Diopterback + (ThicknessMeters * (Diopterfront)2) /
n
Front Vertex Power: (Objective surface toward lens stop) - CORRECT ANSWER✔✔-
Dioptereffective power = Diopterfront + Diopterback + (ThicknessMeters * (Diopterback)2) /
n
Immediately on either side of the visible spectrum are the invisible light segments of:
a) Infrared and ultraviolet
b) X-rays and radio waves
c) Gamma rays and laser
d) Microwaves and radar - CORRECT ANSWER✔✔- a) Infrared light borders the visible
color red and ultraviolet light borders the visible color violet. All of the other answers are
invisible components of the electromagnetic spectrum, but do not abut red or violet.
Which color has the longest wavelength?
a) Red
b) Yellow
c) Green
d) Blue - CORRECT ANSWER✔✔- a) Red has the longest wavelength: 650 nanometers.
Geometric optics includes:
a) The origin of light waves and particles
b) The effects of media on the path of light
c) How light travels through the eye
,d) Physics of the visible light spectrum - CORRECT ANSWER✔✔- b) Geometric optics
involves the reaction of light as it passes through media (any transparent object) or strikes a
surface. Answers a and d refer to physical optics. Physiologic optics defines answer c.
When light bounces back from an object, this is known as:
a) Reflection
b) Refraction
c) Transmission
d) Index of refraction - CORRECT ANSWER✔✔- a) When light strikes an object or an
interface between media with different indices of refraction and bounces back, this is called
reflection.
In reflection, the light rays that hit the object or interface between media with different
indices of refraction are called:
a) Incident rays
b) Reflected rays
c) Refracted rays
d) Transmitted rays - CORRECT ANSWER✔✔- a) The light that hits the object or interface
is termed incident. Those rays that bounce back from the object or interface are called
reflected.
In optics, a medium (or media, plural) is:
a) An object that refracts light
b) An object that emits light
c) An object that reflects light
d) An object through which light passes - CORRECT ANSWER✔✔- d) A medium is a
transparent object through which light can pass. It is not a light source (ie, does not emit
light). It does not necessarily refract light, either (see next question).
When light passes through a transparent medium, it may travel straight through
(Transmission or its path may be altered. This altering or bending property of a medium is
known as:
a) Reflection
b) Refraction
, c) Absorption
d) Tropism - CORRECT ANSWER✔✔- b) The quality of a medium to bend light is called
refraction. In reflection, the rays are bounced off of the surface. Absorbed light does not pass
through a medium. Tropism actually refers to the phenomenon of plants bending toward a
light source.
The ray of light that enters a transparent medium is termed:
a) Incident ray
b) Divergent ray
c) Emergent ray
d) Parallel ray - CORRECT ANSWER✔✔- a) The incident ray is the ray that first strikes and
enters a medium. A divergent ray has been refracted outward. The emergent ray is the ray as
it exits the medium. A parallel ray is straight.
If light passes through a lens and the rays are spread apart on exiting, this is known as:
a) a) Index of refraction (IR)
b) Convergence
c) Zero vergence
d) Divergence - CORRECT ANSWER✔✔- d) If the light is spread apart by the lens, the rays
are said to be divergent.
If light passes through a lens and the rays are bent toward each other on exiting, this is known
as:
a) IR
b) Convergence
c) Zero vergence
d) Divergence - CORRECT ANSWER✔✔- b) Convergence occurs when light rays are
brought together (bent inward) by the lens.
A comparison of the speed of light in air to the speed of light through a substance is:
a) IR (Snell's Law)
b) Angle of refraction
c) Internal reflection
