Answer:
2.82 D
Explanation:
Near point of the person eye is 85 cm that is [tex]u=85\ cm[/tex]
He wants to see the object at 25 cm so [tex]v=25\ cm[/tex]
For the lens we know that [tex]\frac{1}{f}=\frac{1}{v}-\frac{1}{u}[/tex]
[tex]\frac{1}{f}=\frac{1}{25}-\frac{1}{85}[/tex]
\frac{1}{f}=0.04-0.01170=0.02823
[tex]f=35.41\ cm[/tex]
We know that power of the lens [tex]P=\frac{1}{f\ in\ meter}[/tex]
So [tex]P=\frac{1}{0.3541}=2.8235\ D[/tex]
