Civil Engineering - Surveying - Discussion
Discussion Forum : Surveying - Section 1 (Q.No. 22)
22.
Two concave lenses of 60 cm focal length are cemented on either side of a convex lens of 15 cm focal length. The focal length of the combination is
Discussion:
38 comments Page 3 of 4.
Pankaj yadav said:
8 years ago
1/f = 1/60+1/60,
1/f = 1/30.
The combination of concave f = 30
add with convex,
1/f = 1/30+1/15,
1/f =1/10,
f = 10 cm of combination.
1/f = 1/30.
The combination of concave f = 30
add with convex,
1/f = 1/30+1/15,
1/f =1/10,
f = 10 cm of combination.
Pankaj yadav said:
8 years ago
1/f= -1/60-1/60.
1/f= -1/30.
1/f' = -1/30+1/15.
1/f'= 1/30,
f'=30.
1/f= -1/30.
1/f' = -1/30+1/15.
1/f'= 1/30,
f'=30.
Ratan pal said:
8 years ago
I think 1/f=1/15 -1/60 -1/60.
Vamsi said:
8 years ago
Explain this sum cleary.
(1)
PRIYA said:
8 years ago
Explain it clearly.
Rinku singh said:
8 years ago
f1=f2=-60.
1/F1= 1/-60 +1/-60 =1/-30,
F1 =-30 and given F2 = 15,
1/F = 1/-30 +1/15 =1/30,
F =30 ans.
1/F1= 1/-60 +1/-60 =1/-30,
F1 =-30 and given F2 = 15,
1/F = 1/-30 +1/15 =1/30,
F =30 ans.
Akash said:
8 years ago
1/f = 1/f1+1/f2.
1/f = 1/60+1/60.
1/f = 1/30 answer.
1/f = 1/60+1/60.
1/f = 1/30 answer.
(1)
Rafi said:
8 years ago
1/f = -1/f1+1/f2-1/f3
1/f= -1/60+1/15-1/60
1/f = 4/60 -2/60
1/f = 2/60
f = 30cm.
1/f= -1/60+1/15-1/60
1/f = 4/60 -2/60
1/f = 2/60
f = 30cm.
AKSHAY GUPTA said:
8 years ago
Formula: 1/f = 1/f1 + 1/f2.
According to the problem 60 cm on the either side i.e. f1 = f2 = 60 & focal length combination f = ?
Now, 1/f = 1/f1 + 1/f2.
1/f = 1/60 + 1/60.
= 1/30. So combination is 30.
According to the problem 60 cm on the either side i.e. f1 = f2 = 60 & focal length combination f = ?
Now, 1/f = 1/f1 + 1/f2.
1/f = 1/60 + 1/60.
= 1/30. So combination is 30.
Julia roberts said:
8 years ago
1/f=1/f1+1/f2.
concave=-ve.
convex=+ve.
1/f=1/15-(1/60+1/60).
.: f=30.
concave=-ve.
convex=+ve.
1/f=1/15-(1/60+1/60).
.: f=30.
(1)
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