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6. [15 points] Choose one of the following scenarios: A 1.2 cm tall object is 50

ID: 1796197 • Letter: 6

Question

6. [15 points] Choose one of the following scenarios: A 1.2 cm tall object is 50 cm to the left of a converging lens of focal length 40.0 cm. A second converging lens, this one having a focal length of 60.0 cm, is located 150.0 cm to the right of the first lens along the same optic axis. Find the location and height of the final image produced by a. the combination lenses. b.) A 1.2 cm tall object is 50 cm to the left of a converging lens of focal length 40.0cm. A second diverging lens, this one having a focal length of 60.0 cm, is located 300.0 cm to the right of the first lens along the same optic axis. Find the location and height of the final image produced by the combination lenses. Note: Remember to draw an “accurate" ray diagram, use common symbols, and determine a symbolic solution.

Explanation / Answer

6.(B) object distance, p1 = 50 cm

f1 = 40 cm

Applying 1/f1 = 1/p1 + 1/q1

1/40 = 1/50 + 1/q1

q1 = 200 cm

Now this image will work as object for second lens:

object distance, p2 = 300-200 = 100 cm


f = - 60 cm


1/(-60) = 1/100 + 1/q2

q2 = -37.5 cm


final image will formed in between lenses.

37.5 cm left to diverging lens/

m = (q1 / p1) (q2/p2) = hi / ho

-1.5 = hi / 1.2

hi = - 1.8 cm

so image is 1.8 cm high. (inverted)