A) 60 cm
B) 45 cm
C) 30cm
D) 20cm
E) 15cm
Correct Answer: E
Solution :
From the lens formula \[\frac{1}{f}=-\left( \frac{1}{v}+\frac{1}{u} \right)=-\left( \frac{1}{30}+\frac{1}{30} \right)=-\frac{2}{20}=-\frac{1}{15}\] \[\Rightarrow \] \[f=15\,cm\]You need to login to perform this action.
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