- #1

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Two lenses, one converging with focal length 20cm and one diverging with focal length -10cm, are placed 25cm apart. An object is placed 60cm in front of the converging lens. Determine (a) the position and (b) the magnification of the final image formed.

I have a problem with this becasue when i find the image distance after the first len:

[tex]\frac{1}{d_i} + \frac{1}{d_o} = \frac{1}{f}[/tex]

[tex]\frac{1}{d_i} + \frac{1}{60} = \frac{1}{20} [/tex]

[tex] d_i = 30cm [/tex], which is located behind the second len. But i am wondering if the ray pass through the second len, is it going to change its path (See attachment)? If this is so, how can we find the location of the image formed by the first len?

I have a problem with this becasue when i find the image distance after the first len:

[tex]\frac{1}{d_i} + \frac{1}{d_o} = \frac{1}{f}[/tex]

[tex]\frac{1}{d_i} + \frac{1}{60} = \frac{1}{20} [/tex]

[tex] d_i = 30cm [/tex], which is located behind the second len. But i am wondering if the ray pass through the second len, is it going to change its path (See attachment)? If this is so, how can we find the location of the image formed by the first len?