One question when we have a unpolarized ray and enters the polarized

[elabed haidar]

one question when we have a unpolarized ray and enters the polarized sheet it becomes polarized right , after that if i want to enter it to another polarized sheet with angle alpha with the y-axis there is a formula to find the intensity of the new light which is proportional to an angle I=I0 cos^2(angle) here is my question what is this angle i couldn't slove one question right due to this angle can you please help me know how to specify this angle once and for all?? thank you

 

[sophiecentaur]

It's the angle between the E vector of the incident light and the (defined) plane of polarisation of the polariser. When orientated parallel with the incoming polarisation (angle = zero) you get everything through and when at right angles, you get nothing.

Have you looked at any diagrams in the hundreds of www pages which Google can give you? What I have seen has not been confusing or contradictory.

This is easy as long as you restrict your attention to the E field. The H field takes care of itself.

 

[elabed haidar]

thank you very much i got it and yes I've looked and got what i needed to know one thing why doesn't it interfere with the magnetic field??

 

[sophiecentaur]

Of course it interferes with the Magnetic Field. EM waves have transverse E and M fields which are at right angles. By selecting a particular component of the E field you are also selecting a particular component of the H field.
The point I am making is that you only need to specify what happens to the E field - what happens to the H field follows naturally so you don't need to state it.