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 2 of 4.
TSKD said:
7 years ago
Since two cancave is sandwitched with one convex ie.,
1/f = 1/60 + 1/60 - 1/15,
1/f = 1/30.
1/f = 1/60 + 1/60 - 1/15,
1/f = 1/30.
(6)
Avinash said:
8 years ago
1/60 = 1/15 + 1/f2
if we solve, it is coming 20.
Then how it is 30? Anyone explain me.
if we solve, it is coming 20.
Then how it is 30? Anyone explain me.
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.
Ravi said:
1 decade ago
1/f = 1/f1+1/f2.
1/60 = 1/15+1/f2.
1/60-1/15 = 1/f2.
1/f2 = 1/30.
f2 = 30.
1/60 = 1/15+1/f2.
1/60-1/15 = 1/f2.
1/f2 = 1/30.
f2 = 30.
(1)
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)
Nitin said:
1 decade ago
1/f = 1/f1 + 1/f2.
1/f = 1/60 + 1/60.
= 1/30. So combination is 30.
1/f = 1/60 + 1/60.
= 1/30. So combination is 30.
R@ghv said:
9 years ago
It's a three lens combination so I agree with you @Sammer Kashmiri.
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.
Manasa reddy said:
1 decade ago
If we substitute d values in above formula am getting f2=20.
Sammy said:
9 years ago
1/f = 1/f1 + 1/f2.
1/60 = 1/15 + 1/f2.
So, f2 = 30.
1/60 = 1/15 + 1/f2.
So, f2 = 30.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers