A) \[-\,0.5\text{ }D\]
B) \[+\,1.0\text{ }D\]
C) \[-\,1.0\,D\]
D) \[+\,2.0\,D\]
Correct Answer: A
Solution :
When the image of the object which is at infinity, it should be formed at 2 m So, \[\frac{1}{v}-\frac{1}{u}=\frac{1}{f}\] or \[\frac{1}{f}=\frac{1}{-2}-\frac{1}{-\,\infty }\] \[f=-\,2m\] Now the power of lens \[P=\frac{1}{f}=\frac{1}{-\,2}=-\,0.5\,D\]
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