Measuring Intensity of Light After Polarization: Experiments to Confirm Malus' Law

[ellion71]

Part of my independant investigation requires me to carry out an experiment, which when I graph results, would confirm Malus' Law.

I plan on using a bulb as my ambient source and two polarizing lenses. I will then measure the intensity of the light after polarization. Hopefully, if i graph the angle of the analyzing polarizer against intensity I will get a Cosine curve.

However, I am not quite sure on how to measure the intensity of the light after polarization.

Thanks in Advance
Any help/advice would be much appreciated.


P.S
My lecturer has suggested using a irradiance detector which measures in LUX but I am not sure how to convert a value in LUX to a value in W/m^2.

 

[kuruman]

You don't need to convert. The ratio of the intensity after the polarizer to the ratio of the intensity before the polarizer is all you need to know in order to confirm Malus' Law.

 

[kerimek]

I would suggest using a photometer to measure the intensity of light after polarization. A photometer is a device specifically designed for measuring the intensity of light in a specific direction. It works by converting the light energy into an electric current, which can then be measured and converted into units of power per unit area (such as W/m^2). This measurement will provide a more accurate and precise result compared to using a simple bulb and polarizing lenses.

Another important factor to consider in your experiment is controlling for external factors that may affect the intensity of light, such as ambient light or temperature. You may need to conduct the experiment in a controlled environment to ensure accurate and consistent results.

Additionally, to confirm Malus' Law, it is important to vary the angle of the analyzing polarizer and record the corresponding intensity values. This will allow you to plot a graph and observe the expected cosine curve, which confirms the law.

In conclusion, using a photometer and controlling for external factors will help you accurately measure the intensity of light after polarization and confirm Malus' Law. I hope this advice helps and wish you success in your experiment.