A) \[{{f}_{v}}<{{f}_{r}}\] and \[{{F}_{v}}>{{F}_{r}}\]
B) \[{{f}_{v}}<{{f}_{R}}\] and \[{{F}_{v}}<{{F}_{r}}\]
C) \[{{f}_{c}}>{{f}_{r}}\] and \[{{F}_{v}}>{{F}_{r}}\]
D) \[{{f}_{v}}>{{f}_{r}}\] and \[{{F}_{v}}<{{F}_{r}}\]
Correct Answer: B
Solution :
According to lens makers formula \[\frac{1}{f}=(\mu -1)\ \left( \frac{1}{{{R}_{1}}}-\frac{1}{{{R}_{2}}} \right)\Rightarrow \frac{1}{f}\propto (\mu -1)\] Since \[{{\mu }_{Red}}<{{\mu }_{violet}}\] \[\Rightarrow {{f}_{v}}<{{f}_{r}}\]and \[{{F}_{v}}<{{F}_{r}}\] Always keep in mind that whenever you are asked to compare (greater than or less than) u, v or f you must not apply sign conventions for comparison.You need to login to perform this action.
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