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Initially Vertically Polarized Light

Patrick Ford
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Hey guys, let's do an example on polarization. Initially, vertically polarized light cares an intensity of 0.55 watts per meter squared. If you had an adjustable polarizer, what angle relative to the vertical would you want to align it so that the intensity of the light exiting the polarizer is 0. watts per square meter? So we know that Oh, our light is initially polarized. It's saying it's initially vertically polarized. So if you have initially polarized light entering a polarization filter, we have to use the equation I equals I not cosine squared of five. If the light was initially UNP polarized, thin passing through any polarization filter would just drop the intensity by half. But this is not the case, okay, so you always have to keep track. Is your light initially polarized? Is your light initially UNP polarized? In this case, it's initially polarized and it's passing through and unknown angle that angle of the polarization filter we can adjust all we know it is the input intensity and we want to adjust it to get a particular output intensity. So we know that the initial intensity is watts per meter squared, and we want the output intensity to be 0.2 watts per meter squared. So we want to find what angle gives us this. So what I'm gonna do is I'm gonna divide I'm not over and deal with the square root. So that tells me cosign of Phi equals the square root of I divided by I'm not, which is just the square root of 0. divided by 0.55 And that's about 06 So if I plug this into a calculator to find out what five my polarization differences, that tells me that my polarization difference is degrees. Okay, so how would you align your polarization? Filter? What angle? Relative to the vertical Would you align it at? You would align it 53 degrees from the vertical right. And that's because your initial polarization was zero degrees relative to the vertical, and five is your polarization difference? Let's say this wasn't initially vertically polarized. What if this was initially polarized? 10 degrees to the vertical. What would you Where would you put your polarization filter while 53 plus 10 would be 63 degrees. Okay, that would be one option. Technically, you can also go in the other direction. And 43 degrees to the left of the vertical would also be an option. Okay, so just remember, five is not necessarily the final answer. Five is the polarization difference. The final answer in this case is 53 degrees from the vertical. Okay, we found that by finding five, obviously. All right, guys, Thanks for watching.