Discussion Forum

Two convex lenses of power 2D and 5D are separated by a distance 1/3 m . The power of optical system  formed is 

Answer:

Explanation:

 Given

 P₁  =2D ; p₂= 3D

 $d=\frac{1}{3}m$

 we know that   $\frac{1}{F}=\frac{1}f_{1}+\frac{1}f_{2}-\frac{d}{f_{1}.f_{2}}$

 Equivalent power,

 $\therefore$ P=P₁+P₂  -d P₁.P₂

 = $2+3-\frac{1}{3}\times2\times3=3D$