A double convex lens made of glass of refractive index `1.56` has both radii of curvature of magnitude `20 cm`. If an object is placed at a distance of 10 cm from this lens, the position of the image formed is

Explanation

Here `mu=1.6,R_(1)=+30 cm,R_(2)=-30 cm`
`(1)/(f)=(mu-1)((1)/(R_(1))-(1)/(R_(2)))=(1.6-1)((1)/(30)+(1)/(30))=0.6xx(2)/(30)=(1)/(25)`
or `f=25 cm`
Using thin lens formula.
`(1)/(v)=(1)/(f)+(1)/(u)=(1)/(25)+(1)/(-12.5)=(1)/(25)`
or `v=-25 cm`
As `m=(h_(2))/(h_(1))=(v)/(u)` or `(h_(2))/(5 cm)=(-25)/(-12.5)` or `h_(2)=10 cm`
So a virtual image of height `10 cm` is formed at a distance of `25 cm` from the lens on the same side as the object.