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, find the position of image formed.

Explanation

Here, `mu = 1.56, R_1 = 20 cm`,
`R_2 = -20 cm, u = -10 cm, v = ?`
As `(1)/(f) = (mu - 1) ((1)/(R_1) - (1)/(R_2))`
`:. (1)/(f) = (1.56 - 1)((1)/(20) + (1)/(20)) = 0.56 xx (1)/(10)`
`f = (10)/(0.56) = 17.86 cm`
As `(1)/(v)-(1)/(u)=(1)/(f) :. (1)/(v)=(1)/(f)+(1)/(u)=(1)/(17.86)+(1)/(-10)`
`v = -22.72 cm`.