A person can focus objects when they lie beyond \(75 \mathrm{~cm}\) from his eyes. The focal length of the lens required to reduce his least distance of distinct visten \(6025 \mathrm{~cm}\) is ____________
A. \(7500 \mathrm{~cm}\) B. \(18.75 \mathrm{~cm}\) C. 25 .00 \(\mathrm{~cm}\) D. \(3750 \mathrm{~cm}\)
Correct Answer: C
Explanation
Using formula \(1 / f=1 / v+1 / u \mathrm{u}=75 \mathrm{~cm}, \mathrm{~V}=25\) \(1 / f=1 / 75+1 / 25 \Rightarrow \frac{25+75}{1875}=\frac{100}{1875}, 100 \mathrm{f}=1875 \mathrm{f}=\)
