A thin lens made of a material of refractive index μ2 has a medium of refractive index μ1 on one side and a medium of refractive index μ3 on the other side. The lens is biconvex and the two radii of curvature have equal magnitude. R. A beam of light travelling parallel to the principal axis is incident on the lens. Where will the image be formed if the beam is incident from (a) the medium μ1 and (b) from the medium μ3?
When the light is incident on the lens (refractive index 
) from medium of refractive
index 
, then according to lens makers formula
Where, u= distance of incident rays from the lens
v = distance of image formed and the lens
R= radius of curvature
Again, after refraction from the lens, the emerging light experiences the refraction because of different refractive index. Hence,
(B)
When the light is incident on the lens (refractive index 
) from medium of refractive index 
, then according to lens makers formula
Again, after refraction from the lens, the emerging light experiences the refraction because of different refractive index. Hence,
therefore, image will be formed at 