You're correct - unpolarised light coming into the first polariser will exit the first one with half the intensity. If the light was polarised parallel to the first polariser, then it would come through with just the initial intensity (minus reflections, etc)
Very good videos! Thank you! One comment: I think in the equation I=I_0 * cos² (theta): I_0 does not represent the intensity before the first polarizer (like in the picture e.g. at 5:22) but after the first polarizer. (because as you explained correctly: when passing through the first polarizer only the e.g. vertical component of each wave gets through the first polarizer; therefore some intensity would be lost from I_0 (as defined by the picture) to I, even if theta=0, which would not match the formula anymore).
Thanks for that, and you're correct. I was thinking in my head of what happens if the light comes in polarised in line with the first polariser. Thanks for noticing! I'll make an edit to the video as soon as I can. Cheers, Mitch
Good luck! You'll do great, I'm sure :) Just remember to stay calm and know that you don't have to finish the entire exam - choose questions wisely and get as many points as you can :)
there's been a mistake, I0 is the intensity before first polarization, and theta is the angle between the electric field vector and the transmission axis. for those questions with two polarizers, it's I1and I2 for the intensity after each polarizer. Great videos otherwise.
![Standing waves [IB Physics SL/HL]](http://i.ytimg.com/vi/B9SRpYBmPZg/mqdefault.jpg)
![Standing waves [IB Physics SL/HL]](/img/tr.png)
At around 4:30, when the light is polarized through the first polarizer, shouldn't it be half the intensity? Thank you.
You're correct - unpolarised light coming into the first polariser will exit the first one with half the intensity. If the light was polarised parallel to the first polariser, then it would come through with just the initial intensity (minus reflections, etc)
Watching this before I take my Physics Paper 2. Very helpful video! Keep it up!
Thanks - good luck on your exam! -Mitch
Very good videos! Thank you! One comment: I think in the equation I=I_0 * cos² (theta): I_0 does not represent the intensity before the first polarizer (like in the picture e.g. at 5:22) but after the first polarizer. (because as you explained correctly: when passing through the first polarizer only the e.g. vertical component of each wave gets through the first polarizer; therefore some intensity would be lost from I_0 (as defined by the picture) to I, even if theta=0, which would not match the formula anymore).
Thanks for that, and you're correct. I was thinking in my head of what happens if the light comes in polarised in line with the first polariser. Thanks for noticing! I'll make an edit to the video as soon as I can. Cheers, Mitch
This is so helpful! Thank you for making this video.
You are so very welcome! Cheers, Mitch
Final ib exams tomr wish me luck :)
Me too. Good luck
wow thats crazy me too
good luck!
Good luck! You'll do great, I'm sure :)
Just remember to stay calm and know that you don't have to finish the entire exam - choose questions wisely and get as many points as you can :)
Electric fields move vertically, not magnetic.
VENGO DE PARTE DEL PROFESOR CARLOS LOAYZA DEME SU MERCH
there's been a mistake, I0 is the intensity before first polarization, and theta is the angle between the electric field vector and the transmission axis. for those questions with two polarizers, it's I1and I2 for the intensity after each polarizer. Great videos otherwise.