Index of refraction for converging lens

In summary, a thin converging lens with radii of curvature of R1=9cm and R2=-11cm and focal points F1 and F2 at 5cm from the center of the lens has an index of refraction of 1.99. This is calculated using the lens maker's equation, taking into account the negative value of R2.
  • #1
vetgirl1990
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Homework Statement


A thin converging lens has radii of curvature of R1=9cm and R2=-11cm. Assume its focal points F1 and F2 are 5cm from the center of the lens. Determine its index of refraction.

Homework Equations


Len's Makers equation: 1/f = (n2 - n1 / n1) (1/R1 - 1/R2)

The Attempt at a Solution


focal length f = 5cm
n1 = air = 1

Plugging in all my known values:
1/5 = (n2 - 1) (1/9 - 1/11)
n2 = 10.9

This value for refractive index doesn't make sense at all... so I'm not sure what I'm doing wrong!
 
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  • #2
Did you take into account that R2 is negative?
 
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Likes vetgirl1990
  • #3
TSny said:
Did you take into account that R2 is negative?
D'oh! What a ridiculous mistake. Yes, with that taken into account the refractive index is 1.99.
 
  • #4
OK, good.
 

What is the index of refraction for a converging lens?

The index of refraction for a converging lens is a measure of how much the lens bends light as it passes through it. It is typically denoted by the symbol "n".

How is the index of refraction for a converging lens calculated?

The index of refraction for a converging lens is calculated by taking the ratio of the speed of light in a vacuum to the speed of light in the material the lens is made of. This is known as Snell's law: n = c/v, where c is the speed of light in a vacuum and v is the speed of light in the material.

What is the relationship between the index of refraction and the focal length of a converging lens?

The index of refraction and the focal length of a converging lens have an inverse relationship. This means that as the index of refraction increases, the focal length decreases, and vice versa.

How does the index of refraction affect the magnification of a converging lens?

The index of refraction does not directly affect the magnification of a converging lens. However, it does affect the bending of light, which can indirectly impact the magnification by changing the position of the image formed by the lens.

Can the index of refraction for a converging lens be changed?

Yes, the index of refraction for a converging lens can be changed by altering the material the lens is made of or by changing the temperature or pressure of the material. It can also be changed by adding layers of different materials with varying refractive indices to the lens.

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