Focal distance of lens submerged in water

In summary, the focal length of a biconvex lens with a radius of curvature of 15 cm is 15 cm in air. When submerged in water with a refractive index of 1.33, the new focal length can be calculated using the equation 1/f = (n-1)(1/R1 - 1/R2), where f is the focal length, n is the refractive index, and R1 and R2 are the radii of curvature. Using this equation, the new focal length is 0.44 cm, indicating that the lens will have a shorter focal length when submerged in water.
  • #1
Gauss M.D.
153
1

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?
 
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  • #2
Gauss M.D. said:

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.
 

Related to Focal distance of lens submerged in water

What is the focal distance of a lens submerged in water?

The focal distance of a lens submerged in water refers to the distance between the lens and the focal point when the lens is placed in water. This distance can vary depending on the refractive index of water and the type of lens being used.

How does the focal distance change when a lens is submerged in water?

When a lens is submerged in water, the focal distance changes due to the difference in the refractive index of water compared to air. This causes the light rays passing through the lens to bend, resulting in a shorter focal distance.

What factors affect the focal distance of a lens submerged in water?

The focal distance of a lens submerged in water can be affected by the curvature and refractive index of the lens, as well as the refractive index of the water. Additionally, the distance between the lens and the object being focused on, known as the object distance, can also impact the focal distance.

Is the focal distance of a lens submerged in water the same as in air?

No, the focal distance of a lens submerged in water is not the same as in air. The refractive index of air is lower than that of water, causing the light rays passing through the lens to bend differently and resulting in a shorter focal distance.

How can the focal distance of a lens submerged in water be calculated?

The focal distance of a lens submerged in water can be calculated using the lens maker's formula, which takes into account the refractive index of the lens and the medium (water) it is submerged in, as well as the curvature of the lens. This formula is: 1/f = (n - 1) * (1/R1 - 1/R2), where f is the focal length, n is the ratio of the refractive indices, and R1 and R2 are the radii of curvature of the two surfaces of the lens.

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