Answer to Question #93859 in Optics for Sridhar

Question

A person can see clearly objects lying between 15cm and 100cm from the eye.what will be the range of his vision if he wears close fitting spectacles having a power of 0.8 D?

Answer 1

$d_{min1}=15cm=0.15m; d_{max1}=100cm=1m;D_{glasses}=0.8D$

$D_{max1}=\frac{1}{d_{max1}}=\frac{1}{1}=1D$

$D_{min1}=\frac{1}{d_{min1}}=\frac{1}{0.15}=6.67D$

$D_{max2}=D_{max1}-D_{glasses}=(1-0.8)=0.2D$

$D_{min2}=D_{min1}-D_{glasses}=(6.67-0.8)=5.87D$

$d_{max2}=\frac{1}{D_{max2}}=\frac{1}{0.2}=5m=500cm$

$d_{min2}=\frac{1}{D_{min2}}=\frac{1}{5.87}=0.17m=16cm$

Answer d_min2=17cm; d_max2=500cm