An equiconvex lens is cut into two halves along (i) XOX' and (ii) YOY' as shown in the figure. Let \[f,\,f',\,f''\] be the focal lengths of the complete lens, of each half in case (i), and of each half in case (ii), respectively. |
Choose the correct statement from the following: [AIPMT 2003] |
A) \[f'=f,\,\,f''=f\]
B) \[f'=2f,\,\,f''=2f\]
C) \[f'=f,\,\,f''=2f\]
D) \[f'=2f,\,\,f''=f\]
Correct Answer: C
Solution :
Initially, the focal length of equiconvex lens is ....(i) |
Case I: When lens is cut along XOX', then each half is again equiconvex with |
Thus, |
Case II: When lens is cut along YOY', then each half becomes plano-convex with |
Thus, |
Hence, |
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