A) -10cm.
B) -10/4 cm.
C) -10/3 cm.
D) None of these
Correct Answer: C
Solution :
[c] \[\frac{1}{f}=\left( \mu -1 \right)\left( \frac{1}{{{R}_{1}}}-\frac{1}{{{R}_{2}}} \right);\] \[R=10cm.\] \[\frac{1}{f'}=\left( 3-1 \right)\left( \frac{1}{-10}-\frac{1}{10} \right),\] \[f'=-\frac{10}{4}\] \[\frac{1}{{{f}_{eq}}}=\frac{1}{20}-\frac{4}{10}+\frac{1}{20}=\frac{2}{20}-\frac{4}{10}\Rightarrow {{f}_{eq}}=-\frac{10}{3}\]You need to login to perform this action.
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