A double convex lens, lens made of a material of refractive index ${\mu }_1$, is placed inside two liquids or refractive indices ${\mu }_2{\text{ and μ}}_3\text{, }$, as shown ${\mu }_2>{\mu }_1>{\mu }_3$ wide, parallel beam of light is incident on the lens from the left. The lens will give rise to 
  

 

 

 analyzing the rays it gives a divergent ray above the axis and
convergent ray below    ${\mu }_2>{\mu }_1>{\mu }_3$

from medium 2
⇒ when light ray enters into medium 1  then moves away from normal

from medium 3
⇒ when light ray enters into medium 1  the moves towards the normal.