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A Question (or two) on light!


aommaster

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ok. I was reading in a book I bought from Canada about polarization of light. What exactly is polariztion. I know it has to do with straighteneing of light waves. But how exactly?

 

And, they also said, that if you stuck a clear plastic fork through two polarization filters, and started to bend the tongs, then the weakest part would appear black. Now what is all this about?!

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ordinary light travels in a wave /\/\/\/\/

but they are not always up and down they can be side to side like a snake od diagonal.

a polaristaion filter allows only the kight that`s moving in a certain direction to pass through it, all others collide and don`t pass the filter.

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the prongs on the fork act as a polaristion filter too, can you fit a penny through the prongs on the fork, well yes you can IF it`s the right way around, if it isn`t, then you cant. light works in the same way, it`s just that the fork is a bigger scale but doing the exact same thing as the filters do :)

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the fork acts as a wave plate and changes the phase of the different components of the light going through it. this is quite difficult to explain here, but I shall have a stab at it, and might draw a diagram in paint.

 

vertically polarised light can also be treated as light polarised in the +/- 45 degree axis, with the two components of the electrical field totally in phase with one another. we will call these 2 components (a) and (b) by sticking the fork in the way and bending it, you are creating a birefringence (that means a different refractice index for different polarisations of light) and this will alter the relative phases. If we change the phase by pi, then the light will come out horizontally. if we change it by pi/2 it will be circular and so on. there are a number of interesting little experiments you can do with a couple of polarising filters and bits of plastic, and you can actually calculate what sort of polarisation of light you are producing as it passes through the material.

 

does anyone want me to type them up?

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