When two lenses are used in combination, the first one forms an image that then

Question

When two lenses are used in combination, the first one forms an image that then serves as the object for the second lens. The magnification of the combination is the ratio of the height of the final image to the height of the object. A 1.20 -tall object is 50.0 to the left of a lens of focal length of magnitude 40.0 . A second lens, this one having a focal length of magnitude 60.0 , is located 300 to the right of the first lens along the same optic axis.

a. Find the location and height of the image (call it I_2) formed by the lens with a focal length of 40.0 if the first lens is diverging and the second lens is a converging.


b. I_2 is now the object for the second lens. Find the location and height of the image produced by the second lens.

Explanation / Answer

You have no units in your question so I will guess its all supposed to be cm. For future posts, please read your question and make sure everything is included and it makes sense. You are also missing some important wording in the questions. For a, you have (call it ). Call it what?

For b you have "b. is now the object..."   what is now the object?

I think I have guessed right, but make sure you proof read your questions before and after you post to verify everything needed is there. I am going to guess to solve this problem so I hope I am not just wasteing my time.

Part A)

Use the lens equation...

1/f = 1/p + 1/q

1/40 = 1/50 + 1/q

q = 200 cm (So the image is 200 cm the the right of this lens)

The height is...

h'/h = -q/p

h'/1.20 = -200/50

h' = - 4.8 cm   (The negative means inverted)

Part B)

Since the image for the first is 200 cm to the right of the lens, and the second lens is 300 cm to the right, that means that this image, which becomes the object for the second lens, is 100 cm to the left of that second lens

1/-60 = 1/100 + 1/q

q = -37.5 cm   (This means the image is 37.5 cm to the left of this second lens)

h'/h = -q/p

h'/-4.8 = -(-37.5)/(100)

h' = 1.8 cm   (It is upright - re-inverts)

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.