Focal distance of lens submerged in water

[Gauss M.D.]

Homework Statement

A biconvex lens with radius of curvature 15 cm has a focal length of 15 cm in air. What is its focal length if it is submerged in water (n=1.33)?

Homework Equations

1/f = (n-1)(1/R1 - 1/R2)

The Attempt at a Solution

1/f = 1/0.15 = (n-1)(2/0.15)

Solving for n gives n = 1.5

So the new equation will be:

1/f = (1.5 - 1.33)(2/0.15) = 2.27

f = 0.44

What am I doing wrong?

 

[Saitama]

Homework Statement

A biconvex lens with radius of curvature 15 cm has a focal length of 15 cm in air. What is its focal length if it is submerged in water (n=1.33)?

Homework Equations

1/f = (n-1)(1/R1 - 1/R2)

The Attempt at a Solution

1/f = 1/0.15 = (n-1)(2/0.15)

Solving for n gives n = 1.5

So the new equation will be:

1/f = (1.5 - 1.33)(2/0.15) = 2.27

No. Refer your textbook or notes again.