Question

There is an equiconvex glass lens with radius of each face as R and = 3/2 and
au = 4/3. If there is water in object space and air in image space, then the focal length is​

Answer 1

Answer:

the right answer will be 3R/2...

Answer 2

The focal length is 3R/2

Given-

• Radius of each face = R
• μg = 3/2
• μw = 4/3

Focal length can be given by -

1/f = (μ-1) (1/R₁ - 1/R₂)

where f is focal length, μ is refractive index and R is radius of curvature.

1/f = n₂ - n₁/R₁ + n₃ - n₂/R₂

By substituting the values we get

1/f = 3/2-4/3 / R + (1 - 3/2) / -R

f = 3R/2

Refer to the attached image for more details.