need help with capa questions....

[Evergreen]

Two polarizers are oriented at 35.7o to each other and plane-polarized light is incident on them. If only 11.9 percent of the light gets through both of them, what was the initial polarization direction of the incident light?


White light containing wavelengths from 391 nm to 758 nm falls on a grating with 7770 lines/ cm. How wide is the first-order spectrum on a screen 2.40 m away?




just two questions, i have no clue.... :redface:

[Doc Al]

Two polarizers are oriented at 35.7o to each other and plane-polarized light is incident on them. If only 11.9 percent of the light gets through both of them, what was the initial polarization direction of the incident light?
Are you familiar with Malus' Law? It says that if linearly polarized light passes through a polarizer, the intensity of the light transmitted is I = Iincidentcos2(θ), where θ is the angle between the polarization direction of the incident light and the polarization axis (transmission axis) of the polarizer. White light containing wavelengths from 391 nm to 758 nm falls on a grating with 7770 lines/ cm. How wide is the first-order spectrum on a screen 2.40 m away?

Take a peek at these threads:
http://www.physicsforums.com/showthread.php?t=16902
http://www.physicsforums.com/showthread.php?t=17047

[Evergreen]

i need a numeric answer, for the second quesiton that I am posting, i did use a similar method, but my answer is still wrong

[Doc Al]

i need a numeric answer, for the second quesiton that I am posting, i did use a similar method, but my answer is still wrong
Show your work and I'll take a look.

[PrettyMz4Christ]

[QUOTE=Doc Al]Are you familiar with Malus' Law? It says that if linearly polarized light passes through a polarizer, the intensity of the light transmitted is I = Iincidentcos2(θ), where θ is the angle between the polarization direction of the incident light and the polarization axis (transmission axis) of the polarizer.
QUOTE]
I have a question on this also...
I am fairly new with this material, and I know that I am trying to find theta, but what do I plug in for I and Io? Is there any good reading online for this?

[Doc Al]

I have a question on this also...
I am fairly new with this material, and I know that I am trying to find theta, but what do I plug in for I and Io?
That depends on what you are given in the problem. If you have a specific problem, post it and your work and I'll take a look. (You might want to start a new thread.)

I give a brief description of Malus' law in my earlier post.
Is there any good reading online for this?
Do a search on Malus' Law and you'll find plenty. Here's one place to start: http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/polcross.html#c3

Welcome to PF!