A person having short-sight cannot see objects clearly beyond a distance of 1.5 m. What would be the nature and power of the corrective lens to restore proper vision?
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Concave lens should be used to restore proper vision.Calculation of power:
Here, far point of myopic eye = 1.5m The object kept at infinity can be seen dearly if the image of this object is formed at 1.5m. So, object distance, $\text{u}=\infty$ image distance, v = 1.5m$\frac{1}{\text{v}}-\frac{1}{\text{u}}=\frac{1}{\text{f}}$
$\frac{1}{-1.5}-\frac{1}{\infty}=\frac{1}{\text{f}}$
$\text{f}=-1.5\text{m}$
$\text{p}=\frac{1}{\text{f}}=\frac{1}{-1.5}=-0.67\text{D}$
Here, far point of myopic eye = 1.5m The object kept at infinity can be seen dearly if the image of this object is formed at 1.5m. So, object distance, $\text{u}=\infty$ image distance, v = 1.5m$\frac{1}{\text{v}}-\frac{1}{\text{u}}=\frac{1}{\text{f}}$
$\frac{1}{-1.5}-\frac{1}{\infty}=\frac{1}{\text{f}}$
$\text{f}=-1.5\text{m}$
$\text{p}=\frac{1}{\text{f}}=\frac{1}{-1.5}=-0.67\text{D}$
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