How Do You Calculate the Index of Refraction for a Lens?

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Homework Help Overview

The problem involves calculating the index of refraction for a convex lens given its radii of curvature and focal length. The context includes identifying the type of glass based on the calculated index of refraction.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the application of the lens maker's formula and question the meaning of identifying the type of glass. There are requests for step-by-step guidance in solving the equation.

Discussion Status

Some participants have attempted calculations using the provided formula, while others seek clarification on the type of glass and the reasoning behind it. There is an ongoing exploration of the calculations without a definitive consensus on the final interpretation.

Contextual Notes

Participants express uncertainty about the specific type of glass and the implications of the index of refraction values. The discussion includes a mix of assumptions about the lens properties and the expected outcomes based on the calculations.

AlanxD
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Homework Statement


Suppose a convex lens is ground so that one surface has a radius of curvature of 30.0 cm and the opposing surface has a radius of curvature of 40.0 cm. The focal length is 34.2cm. What is the index of refraction of the lens? What kind of glass is the lens?

Homework Equations



Need help by using the formula
1/f=(n-1)(1/R1+1/R2).

The Attempt at a Solution



I knw R1=30 cm
R2=40 cm
f=34.2 cm
I can't finish finding n.
 
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What is meant by what type of glass is it? Is that supposed to mean if it is converging or diverging?
 
Like is it suppose to be crown glass, quartz, zircon, etc.
Can someone help solve the equation step by step and tell me what glass it is.
 
Well using the formula given I got Crown Glass for the lens. Did you plug in the knowns into the equation?
 
Ya i did but can u type it step by step i knw how to plug it in the equation but i dun got that number.
 
1/34.2=(n-1)(1/30 + 1/40)

.0313= (n-1)(.0333 + .0250)

.0313/.0583 = (n-1)

.537=n-1

n=1.54

Index of Refraction of Crown Glass 1.50-1.62
 
thanks a lot.
 

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