# Combination lens equation questions

• Mr.somebody
In summary, the conversation discusses the use of lenses and equations needed to calculate the distance and angle of light rays passing through them. The thin-lens equations are recommended and it is mentioned that the refractive index within the lens does not need to be accounted for. The focal lengths of the lenses may need to be measured for accuracy.
Mr.somebody
Homework Statement
Lens questions.
Relevant Equations
idk
Homework Statement: Lens questions.
Homework Equations: idk

Hello, so I was wanting to use a laser beam and purchase a few lens' online for a project and wanted to get something similar to the image below, where i would end with a horizontal light ray i was wondering if anyone knows the equations that would be required to figure out the distance from each of the lens to the focal point and the angle at which the bend at from lens to lens to the focal point. I suppose I would also have to account for the refraction within the lens also, so is their anything i can use to account for that as well.
THANK YOU SO MUCH

Hi,
Mr.somebody said:
end with a horizontal light ray
Seems to me you start out with a horizontal (?) light ray and end up with a diverging beam after the focal point...
Mr.somebody said:
Homework Equations: idk
Let me revert that: what do you know ? about lenses and imaging ?

Mr.somebody said:
Hello, so I was wanting to use a laser beam and purchase a few lens' online for a project and wanted to get something similar to the image below, where i would end with a horizontal light ray i was wondering if anyone knows the equations that would be required to figure out the distance from each of the lens to the focal point and the angle at which the bend at from lens to lens to the focal point.

Thin-lens equations should suffice to get you started, assuming you don't need millimeter-scale precision or better. Try this site and see if it helps: https://courses.lumenlearning.com/boundless-physics/chapter/lenses/

Note that you may actually need to measure the focal lengths of your lenses. Even if they are given, it never hurts to check.

Mr.somebody said:
I suppose I would also have to account for the refraction within the lens also

Not true. Lenses like these always have a single refractive index that does not vary as the light travels through the material. All you need to account for is the change in the refractive index at each surface.

## 1. What is the combination lens equation?

The combination lens equation is a formula that describes the relationship between the object distance (u), image distance (v), and focal length (f) of two or more lenses that are placed in a series. It is given by 1/v = 1/u + 1/f.

## 2. How do you use the combination lens equation?

To use the combination lens equation, you need to know the object distance (u) and focal length (f) of each lens. Then, you can plug these values into the equation to solve for the image distance (v). This tells you where the final image will be formed after light passes through both lenses.

## 3. Can the combination lens equation be used for any type of lens?

Yes, the combination lens equation can be used for any type of lens, including convex, concave, and even combinations of both. However, it is important to note that the equation assumes thin lenses and paraxial rays, so it may not be accurate for more complex optical systems.

## 4. What happens if the lenses have different focal lengths?

If the lenses have different focal lengths, the combination lens equation can still be used. However, the resulting image distance (v) will be different depending on the relative positions of the lenses and their focal lengths. The magnification of the image may also be affected.

## 5. Can the combination lens equation be used for more than two lenses?

Yes, the combination lens equation can be extended to include more than two lenses in a series. In this case, the equation becomes 1/v = 1/u + 1/f1 + 1/f2 + ..., where f1, f2, etc. are the focal lengths of each lens. This allows for the calculation of the final image distance after passing through multiple lenses.

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