Quiz 4 - Lens Materials & Designs

Question 1

The following are advantages of glass:

a. Superior optics and low chromatic aberration
b. Very scratch prone and heavy
c. Low abbe and resistant scratching
d. Heavy and inferior optics

Answer 1

a. Superior optics and low chromatic aberration

Question 2

CR39 is:

a. Tintable and scratch proof
b. Somewhat scratchable and very thin
c. Tintable and somewhat scratchable
d. Tintable and very thin

Answer 2

c. Tintable and somewhat scratchable

Question 3

Polycarbonate is

a. Used as a safety material
b. All of these
c. Low abbe value
d. Light weight

Answer 3

b. All of these

Question 4

High index lenses are rarely used for:

a. Rimless glasses
b. Sunglasses
c. Reading glasses
d. Safety glasses

Answer 4

d. Safety glasses

Question 5

What is the approximate speed of light in air?

a. 186,000 miles per second
b. 186,000 miles per minute
c. 186,000 mph
d. None of the above

Answer 5

a. 186,000 miles per second

Question 6

What happens to light as it passes from air into a refractive material such as glass?

a. It speeds up
b. It stops
c. It slows down
d. It does not change speed

Answer 6

c. It slows down

Question 7

Index of refraction is ratio of the speed of light in the material to the speed of light in:

a. Water
b. A solid
c. Air
d. A lens

Answer 7

c. Air

Question 8

Put the following lens materials in order of weight from heaviest to lightest:

a. Glass, high index, CR39, polycarbonate
b. Glass, polycarbonate, CR39, high index
c. Glass, CR39, high index, polycarbonate
d. Glass, CR39, polycarbonate, high index

Answer 8

c. Glass, CR39, high index, polycarbonate

Question 9

Trifocals have how many focal points?

a. Four
b. Two
c. One
d. Three

Answer 9

d. Three

Question 10

Hi index is the most impact-resistant lens material.

a. True
b. False

Answer 10

b. False

Question 11

Glass is the most scratch-resistant lens material.

a. True
b. False

Answer 11

a. True

Question 12

A stocked lens already prepared with a power is known as a _______ lens.

a. Finished
b. Plano
c. Semi-finished
d. Plus

Answer 12

a. Finished

Question 13

To surface a prescription a/an ______ lens should be selected.

a. Edged
b. Semi-finished
c. Uncut
d. Finished

Answer 13

b. Semi-finished

Question 14

The following is a disadvantage of glass:

a. High abble value
b. Light weight
c. Poor impact resistance
d. Scratch resistant

Answer 14

c. Poor impact resistance

Question 15

The blank size of a lens is measured in …

a. Centimeters
b. Millimeters
c. Meters
d. Inches

Answer 15

b. Millimeters

Question 16

The true curve of a lens is determined from the sag value.

a. True
b. False

Answer 16

a. True

Question 17

A bifocal lens has:

a. Four focal points
b. Three focal points
c. One focal point
d. Two focal points

Answer 17

d. Two focal points

Question 18

Put the following lenses in order of index of Refraction, lowest to highest.

a. CR-39, Crown Glass, Hi-index, Trivex, Polycarbonate
b. CR-39, Crown Glass, Trivex, Polycarbonate, Hi-index
c. Hi-index, CR-39, Trivex, Polycarbonate, Crown Glass
d. Trivex, Polycarbonate, Hi-index, CR-39, Crown Glass

Answer 18

b. CR-39, Crown Glass, Trivex, Polycarbonate, Hi-index