A) 40 cm
B) 20 cm
C) 80 cm
D) 30 cm
Correct Answer: A
Solution :
By formula \[\frac{1}{f}=(\mu -1)\,\left( \frac{1}{{{R}_{1}}}-\frac{1}{{{R}_{2}}} \right)\] = \[(1.5-1)\left( \frac{1}{40}+\frac{1}{40} \right)=0.5\times \frac{1}{20}=\frac{1}{40}\] \[\therefore \] \[f=40\]\[cm\]You need to login to perform this action.
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