The dotted part of the lens is cut & kept along the x-axis as shown.
If parallel paraxial rays fall on this system, the coordinate of the image formed after refraction from both the lenses is (30,-1).
If a=2.5 cm, Find "b" & the focal length of the lens.
(Assume that the lens has no Spherical Aberration.)
13Arrey bhaiya koi toh try maaro, mera chaar page mein bhi answer nahi aaya,,,,,pata nahi kahaan se 3 minute mein karne ka sawaal hai......
[336] ...Am popped up now.....!!!
1first we need to find (b-a)
assuming both are in contact and thin enough and the origin at the optical centre of the 1st lens.
if focal length = f
then net focal lenth = f/2
clearly f/2 = 30 cm => f = 60cm.
also using for the smaller part
m = vu = 1/2
=> x = (b-a)/2
2= b-a => b = 4.5
btw it is definitely not even a 3 minutes q
13I never assumed tht "both are in contact", how have v got the right to use tht (its not even represented in the figure tht way!) ??? [7]
I kept tht part some "d" dist. away n was using all sorts of similarity conditions n was getting 2 bi-quadratics to solve; thts why took me 4 pgs...
btw, answers are right...but do respond to my query...
13The first img. is formed at 60cm (when both of them act as a combination.)
This img. then acts as a virtual source fr the cut part, hence forming the final img. at (30,-1).
So, fr the cut part , u =60, v=30 => m =1/2.
1Assuming ofcourse that the origin was mentioned in your question it would not be possible to calculate anything unless that distance "d" was given...
