Question

question.
One surface of a convergent lens of focal length 20 cm is
convex. Its radius of curvature is 25 cm. What is the radius
of curvature of the other surface if the refractive index of
material of the lens is 1.5.
(Ans. - 16.67 cm)​

Answer 1

Answer:

From Lens makers formula,

f

1

=(μ−1)(

R

1

1

−

R

2

1

)

R

1

=∞

R

2

=−20 cm

f

1

=(1.5−1)(

20

1

)

f=40cm

Answer 2

Answer:

From Lens makers formula, f1=(μ−1)(R11−R21)

R1=∞

R2=−20 cm

f1=(1.5−1)(201)

f=40cm