Lab 2 - Lab # 2: Measurement of Light Intensity as a Function of Distance from a Light PDF

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Lab # 2: Measurement of Light Intensity as a Function of Distance from a Light Source

Purpose: The purpose of this lab is to determine the relationship between light intensity and the distance between the source and detector also to understand how the shape of light source changes this ...

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Lab # 2: Measurement of Light Intensity as a Function of Distance from a Light Source Purpose: The purpose of this lab is to determine the relationship between light intensity and the distance between the source and detector also to understand how the shape of light source changes this relationship (using loggerPro). Expectations: Our expectations are to see that as distance increases that the intensity of light will decrease by the square of the distance.

The inverse square fit is less representative of the curve because it does not take into account background values. Thats why the new fit its able to better match the curve. As represented in the graph above. Red line: Light bulb Green line: LED lights When we measured the background these are the values we obtained: C= 11.8 lux, our curve fit gives us a C value of -23.33 lux for light bulb and 1055 lux for LED lights B=19.1 lux, our curve fit gives us a B value of .1226 lux for light bulb and -0.4694 lux for LED light 1. The data shows that as distance increases, the intensity of light decreases by the square of the distance. The function I=A/(x+B)^2 +C gives a better fit than the function I=A/x^2.

2. Our results are consistent with Gauss’s law. The shape of the graph of our best fit demonstrates that light intensity is inversely proportional with the value of distance squared. This is exactly what the Gauss’s law states.

Conclusion Apart from improper measurement and equipment inaccuracy, other possible sources of error include the light sensor and LoggerPro not working properly. Unaccounted background light could have impacted the data. The sensor also could not have been aligned properly with each light source. For the light bulb, our expectations matched our results because the data was best fit to the equation I=A/(x+B)^2 +C, which indicates that the intensity of the light decreased by the square of the distance. For the LED lights, however, the data did not match our expectations. The I=A/ (x+B)^2 +C line did not exactly match our data and, more importantly, the intensity of the light was constant up until a certain distance. Therefore, we conclude that the shape of the light does affect the relationship between light intensity and distance. Feedback We learned how to use logger pro and enjoyed working with our own data. We appreciated quantitatively analyzing the relationship between light intensity and distance in view of the physics concepts we learned in class. Furthermore, we also deepened our understanding of the different ways LED versus incandescent light bulbs operate....