Lens power Flashcards
Find the focal lengths of the given lenses.
a. D = +2.00D f = ___mm
b. D = +10.00D f = ___mm
c. D = -0.50D f = ___cm
d. D = -2.50D f = ___mm
a. f = .5 M
b. f = 100mm
c. f = 200cm
d. f = 400mm
Find the dioptric power of lenses having the following focal lengths.
a. f = +4.0 meters, D = ___
b. f = +20mm, D = ___
c. f = -333mm, D = ___
d. f = -25cm, D = ___
a. D = +0.25D
b. D = +50.00D
c. D = -3.00
d. D = -4.00
What is the dioptric power of a lens with a focal length of each of the following?
a. 25mm = ___
b. 2.5mm = ___
c. 25cm = ___
a. 40.00D
b. 400.00D
c. 4.00D
What is the focal length of a +5.00D lens in ___
a. Meters? = ___
b. Millimeters? = ___
a. .2
b. 200
What is the focal length of a +0.50D lens in ___
a. Centimeters? = ___
b. Meters? = ___
a. 200
b. 2
What dioptric power is required to focus at 40cm?
+2.50D
What is the focal length of a +3.00D lens in centimeters?
33cm
What is the power of a lens if it brings incident light to a focus 20mm away?
+50.00D
What is the focal length of a -0.50D lens?
-2M
What is the focal length of a -2.50D lens in centimeters?
-40cm
What is the power of a lens with a virtual focus 40mm away?
-25.00D
What is the power of a lens with real focus 4M away?
+0.25D
What is the focal length of a +10.00D lens in cm?
10cm
What is the focal length of a +1.00D lens in meters?
1M
A +2.50D lens will focus light ___ mm away.
400
A lens focuses light 4M away. What is the power of the lens?
+0.25D
A minus lens has a focal length of 25cm. What power is the lens?
-4.00D
A lens with a focal length of 80cm is a ___
+1.25D lens
Find the nominal power
1
Find the back surface
2
Find the front surface
3
4
-4.50D
5
+7.00D
6
-11.00D
Sagittal depth is the straight-line distance between the back surface of a lens at its vault and the chord diameter of the lens.
true or false
true
If the radius of a surface remains the same and the diameter changes, the thickness will change but the sagittal depth will remain the same.
true or false
false
If the radius of a surface is reduced and the diameter remains the same, the thickness will be reduced.
true or false
true
If the sagittal depth remains the same, and the diameter increases, the surface will become flatter.
true or false
true
If the sagittal depth remains the same, and the diameter increases, the surface will become flatter.
true or false
true