Determine dispersion from fitting equation

In summary, the question asks for the dispersion at a wavelength of 800 nm, using a fitting equation from a graph of n vs. 1/lambda^2. The equation given is y = 7e-15x + 1.60, where x is 1/lambda^2. The solution attempted involved taking the derivative of 1/lambda^2 to get -2/lambda^3 and plugging in the value for n. However, the answer did not match previous findings. The conversation also suggests that there may have been an error in trying to fit a new curve of n vs. lambda.
  • #1
mufc4ever
5
0

Homework Statement



Determine the dispersion (dn/d lambda) at a wavelength of 800 nm from fitting equation.


Homework Equations



Fitting equation from graph of n vs 1/lambda^2

y = 7e-15 x + 1.60


The Attempt at a Solution



Since it is a plot of n vs 1/lambda^2 I thought that x would be 1/lambda^2 so I took the derivative of that to get -2/lambda^3 and then put in the number. However I did not get a correct answer consistent with earlier findings.

What am I doing wrong?
 
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  • #2
Looks like you went dn/d(1/λ2) = (dn/dλ)(dλ/d(1/λ2)
= (-2/λ3)dn/dλ
which is what I would have done.

That math has to be correct, so you probably erred somewhere along the line in trying to fit a new curve of n vs. λ. That curve of course should look close to a straight line ...

How about giving us a few numbers you computed?
 

What is dispersion?

Dispersion refers to the measure of how spread out a set of data is. It describes the variability or diversity within the data.

How is dispersion determined from fitting equations?

Dispersion can be determined from fitting equations by examining the residuals, which are the differences between the predicted values from the equation and the actual observed values. The magnitude of the residuals can indicate the amount of dispersion in the data.

What is the relationship between dispersion and fitting equations?

The fitting equation is used to model the data and determine the best fit line or curve. Dispersion is a measure of how well the data points fit the line or curve. A smaller dispersion indicates a better fit, while a larger dispersion suggests that the model is not accurately representing the data.

What factors can affect the determination of dispersion from fitting equations?

The determination of dispersion can be affected by outliers in the data, the type of fitting equation used, and the number of data points. Outliers can greatly impact the residuals and skew the measure of dispersion. The type of fitting equation used can also affect the sensitivity to outliers. Additionally, a larger number of data points can provide a more accurate measure of dispersion.

How can dispersion be used in data analysis?

Dispersion can be used to determine the reliability of the model and the accuracy of the data. It can also help identify patterns or trends in the data and provide insights into the underlying factors that contribute to the variability. Additionally, dispersion can be used to compare different models and determine which one best fits the data.

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