Calculate the focal length of a planoconvex lens?

In summary, the focal length of a planoconvex lens can be calculated using the equation 1/f = 1/v + 1/u, where f represents the focal length, v represents the image distance, and u represents the object distance. To find the focal length in this scenario, the equation would be 1/f = 1/62.5 + 1/25, resulting in a focal length of approximately 45.45 cm.
  • #1
givemeknowledge
8
0

Homework Statement



Calculate the focal length of a planoconvex lens that produces a real image 2.5 times as big as the object if the object is 2.5 cm from the lens?

Homework Equations



The only one I can think of is 1/f = 1/v + 1/u

The Attempt at a Solution


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My 'attempt' is 1/f = 1/62.5 + 1/25 = 0.056 but this just seems totally wrong.

Had a whirl at it, but cannot produce an answer, any help would be really appreciated!
 
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  • #2
givemeknowledge said:
The only one I can think of is 1/f = 1/v + 1/u

I'm not familiar with u and v in these equations. I think my class labels them differently. What do they represent here?
 
  • #3
You have to invert the answer to get f :)
 

What is the formula for calculating the focal length of a planoconvex lens?

The formula for calculating the focal length of a planoconvex lens is f = R/(n-1), where f is the focal length, R is the radius of curvature of the convex side, and n is the refractive index of the lens material.

What information do I need to know to calculate the focal length of a planoconvex lens?

You will need to know the radius of curvature of the convex side of the lens and the refractive index of the lens material.

Can I use this formula for any size planoconvex lens?

Yes, this formula can be used for any size planoconvex lens as long as you have the necessary information about the lens.

How accurate is this formula for calculating the focal length of a planoconvex lens?

This formula provides a good approximation for the focal length of a planoconvex lens, but it may not be completely accurate due to factors such as lens imperfections and environmental conditions.

Can I use this formula for lenses made of different materials?

No, this formula is specific to planoconvex lenses made of a single material with a constant refractive index. If the lens is made of multiple materials or has a varying refractive index, a different formula would be needed.

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