Is My Planck's Constant Data Incorrect?

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Homework Help Overview

The discussion revolves around an experimental analysis of Planck's constant, focusing on the relationship between voltage and wavelength in light. The original poster presents inconsistent results from their practical work, questioning the expected trend of increasing voltage with decreasing wavelength.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to understand why their results show unexpected values, particularly the voltage readings for yellow light being higher than those for blue light. Participants question the validity of the results and suggest examining the quality of the filters used.

Discussion Status

Participants are actively exploring the discrepancies in the data, with some suggesting that the yellow filter may be transmitting shorter wavelengths. There is a recognition of the need to analyze the results further, but no consensus has been reached on the cause of the anomalies.

Contextual Notes

The original poster mentions using a limited set of filters and expresses uncertainty about systematic errors in their measurements. They also note the challenge of finding resources that explain the anomalies observed in their results.

Procrastinate
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I was doing a practical to analyse for my school assessment with regard to Planck's constant. I was using a Planck's constant kit to get some results but the results I was getting was inconsistent with my research as seen below. Isn't the voltage meant to increase as the wavelength is shorter? My results seem really muddled up and I did it again and it still came out with the same results. Perhaps there is something wrong with the machine or is this just the way it is meant to be?


Aperture Diameter (mm)
7
10
14
20
N/A (fully exposed)

Results aligned with aperture size list (I couldn't put the table on here)

Blue 428nm Voltage (V)
0.37
0.68
1.06
1.31
1.35

Green 460nm
Voltage (V)
0.19
0.34
0.71
0.98
1.01

Yellow 492nm
Voltage (V)
0.77
1.11
1.36
1.50
1.52

Orange 530nm
Voltage (V)
0.28
0.55
0.91
1.13
1.16

Red 590nm
Voltage (V)
0.07
0.15
0.27
0.44
0.48
 
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Your results show that the voltage does increase as the wavelength gets shorter. Red waves were the longest and blue waves the shortest.
 
Dadface said:
Your results show that the voltage does increase as the wavelength gets shorter. Red waves were the longest and blue waves the shortest.

Yes but why is yellow greater than blue? It should be just a bit greater than red.
 
Procrastinate said:
Yes but why is yellow greater than blue? It should be just a bit greater than red.

Oh yes, I see what you mean.First time I just scanned the numbers but your post above forced me to look more carefully.Forget yellow for the moment and the trend for the other wavelengths seems to be correct.Now why the anomalous results for yellow?Did you use filters ?If so these transmit a range of wavelengths and perhaps the yellow filter was of lower quality compared to the others.Perhaps you could look up the characteristics of the filters you used.Of course I'm not familiar with the equipment you used or what you did but your overall results look pretty good to me and I would go ahead and process them anyway.I imagine you would get some pretty good graphical plots with yellow standing out as an anomoly.Don't worry about anomolies,unless you get the opportunity to go back and recheck them experimentally there is nothing you can do about them, but you can write about them and come up with some suggestions as to why they cropped up.
 
Yes I did use filters. Those were the five that were available. I did it again the next day and the results were similar to those.

I can't think of any reasoning for the systematic error as that was my first time ever using it. I also can't find any particular sites that may account for this anomaly online either.
 
My feeling is that the yellow filter was transmitting some shorter wavelength components but I just don't know.Hopefully others will come in here with some suggestions.It seems to me that you have done just about everything you can, so if I was you I wouldn't bother about it and go ahead and process your results.
 

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