# Answers to Extra Credit homework problem set #1

The correct answer is identified by an asterisk

1. If a person has an eye with a near point of 10 cm and a far point of 200 cm, then

(a) The person has myopia and needs eye glasses with a positive lens

*(b) The person has myopia and needs eye glasses with a negative lens

(c) The person needs bifocals

(d) The person has hyperopia and needs eye glasses with a positive lens

(e) The person has hyperopia and needs eye glasses with a negative lens

2. If a person has an eye with a near point of 50 cm and a far point of 60 cm, then

(a) The person has myopia and needs eye glasses with a positive lens

(b) The person has myopia and needs eye glasses with a negative lens

(c) The person has hyperopia and needs eye glasses with a positive lens

(d) The person has hyperopia and needs eye glasses with a negative lens

*(e) The person needs bifocals

3. If a person has an eye with a near point of 200 cm and a far point of infinity, then

(a) The person has myopia and needs eye glasses with a positive lens

(b) The person has myopia and needs eye glasses with a negative lens

(c) The person needs bifocals

*(d) The person has hyperopia and needs eye glasses with a positive lens

(e) The person has hyperopia and needs eye glasses with a negative lens

4. If a person has an eye that has no accommodation, then

(a) The person has myopia and needs eye glasses with a positive lens

(b) The person has myopia and needs eye glasses with a negative lens

*(c) The person needs bifocals

(d) The person has hyperopia and needs eye glasses with a positive lens

(e) The person has hyperopia and needs eye glasses with a negative lens

5. Bifocals are eye glasses with lenses which have two focal lengths: one for viewing objects at a distance and a second for viewing objects up close. When bifocals are worn by a person who has had cataract surgery and has no accommodation,

(a) The strength of the lens for viewing objects at a distance is always negative

(b) The strength of the lens for viewing objects at a distance is always positive

*(c) The strength of the lens for viewing objects up close is always greater than the strength for viewing objects at a distance

(d) The strength of the lens for viewing objects up close is always less than the strength for viewing objects at a distance

(e) None of these statements is always true

6.  An eyeglass lens made from a combination of a positive lens and a cylinder lens would be used for

(a) a person whose eye has no accommodation

(b) a person whose eye has astigmatism and a normal near point

(c) a person whose eye has myopia and astigmatism

*(d) a person whose eye has hyperopia and astigmatism

(e) a person whose eye has presbyopia

7.  A positive lens has a focal length of 5 cm. If that lens is used as a simple magnifier, the magnification relative to the eye acting alone is about

*(a) 5

(b) 10

(c) 0.5

(d) 0.2

(e) 12

8. A compound microscope is made using

(a) a long focal length positive lens for both the objective and the eye piece

*(b) a short focal length positive lens for both the objective and the eye piece

(c) a long focal length positive lens for the objective and a short focal length positive lens for the eye piece

(d) a short focal length positive lens for the objective and a long focal length positive lens for the eye piece

(e) a positive lens for the objective and a negative lens for the eye piece

9. A Galilean telescope is made using

(a) a long focal length positive lens for both the objective and the eye piece

(b) a short focal length positive lens for both the objective and the eye piece

(c) a long focal length positive lens for the objective and a short focal length positive lens for the eye piece

(d) a short focal length positive lens for the objective and a long focal length positive lens for the eye piece

*(e) a positive lens for the objective and a negative lens for the eye piece

10. An astronomical telescope is made using

(a) a long focal length positive lens for both the objective and the eye piece

(b) a short focal length positive lens for both the objective and the eye piece

*(c) a long focal length positive lens for the objective and a short focal length positive lens for the eye piece

(d) a short focal length positive lens for the objective and a long focal length positive lens for the eye piece

(e) a positive lens for the objective and a negative lens for the eye piece

Captain Hook makes a Galilean telescope using two lenses of focal lengths +50 cm and –10 cm.

11. The separation between the two lenses should be

(a) 70 cm

(b) 60 cm

(c) 50 cm

*(d) 40 cm

(e) 30 cm

12. The magnitude of the magnification will be

*(a) 5 and the image is erect

(b) 5 and the image is inverted

(c) 4 and the image is erect

(d) 4 and the image is inverted

(e) 6 and the image is erect