1. If the image distance is equal to the object distance, what is the magnification of the image?

Question

a. 1/4

b. 1/2

c. 1.0

d. 2.0

e. 2.5

A 12 cm tall object is placed 16 cm to the left of a convex lens which has a focal length of 9 cm.

2. Where will the image form?

a. 20.5 cm from the right of the lens

b. 20.5 cm from the left of the lens

c. 5.8 cm from the right of the lens

d. 5.8 cm from the left of the lens

e. 6.9 cm from the right of the lens

3. What kind of image is formed?

a. real, upright

b. real, inverted

c. virtual, upright

d. virtual, inverted

Answer 1

Magnification = image-distance / object-distance...

Answer 1 is c / 1.0

Answer 3 is b / real inverted

Answer 2 is a / ... right of the lens...

let:

f = focal-distance

o = object-distance

i = image-distance

1/f = 1/o + 1/i

http://en.wikipedia.org/wiki/Lens_(optic...

1/9 = 1/16 + 1/i eq 16/(9*16) = 9/(16*9) + 1/i eq

(16-9)/(9*16) = 1/i eq 7/144 = 1/i eq

i = 144/7

Good luck.