A) \[{{\operatorname{f}}_{v}} < {{f}_{R}}\,\,and\,\,\,{{F}_{v}} > {{F}_{R}}\]
B) \[{{\operatorname{f}}_{v}} > {{f}_{R}}\,\,and\,\,\,{{F}_{v}} < {{F}_{R}}\]
C) \[{{\operatorname{f}}_{v}} > {{f}_{R}}\,\,and\,\,\,{{F}_{v}} > {{F}_{R}}\]
D) \[{{\operatorname{f}}_{v}} < {{f}_{R}}\,\,and\,\,\,{{F}_{v}} < {{F}_{R}}\]
Correct Answer: A
Solution :
For a convex lens, \[{{f}_{R}}>{{f}_{v}}\,\,or\,\,{{f}_{v}}<{{f}_{R}}\] For a concave lens, total length is negative \[\therefore \,\,\,\,\,\,\,\,\,\,\left| {{F}_{v}} \right|<\left| {{F}_{R}} \right|\,\,or\,\,{{F}_{v}}>{{F}_{R}}\]
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