Question

What is the focal length of double convex lens for which radius of curvatureof the surface is 40cm?(Given refractive index of glass w.r.t air is 1.5)​

Answer 1

Answer:

anwer is 5/3

Explanation:

Here R

1

= 20 cm, R

2

= -40 cm, f = 20 cm

Using lens maker's formula we get,

20

1

=(μ−1)(

20

1

+

40

1

)

20

1

=(μ−1)

40

3

⇒μ=

3

5