Intensity of Light With a Given Power of Through a Polarizer

[cvangheem]

1. Homework Statement
A 200 mW horizontally polarized laser beam passes through a polarizing filter whose axis is 25 degrees from vertical.

What is the power of the laser beam as it emerges from the filter?
P=mW

2. Homework Equations

I₀cos²(theta)
I≈E₀cos(theta)
I=E₀cos²(theta)
I=P/A=(E₀²)/(cμ₀)=(cε₀E₀²)/2

3. The Attempt at a Solution
I have tried numerous ways and I still can't seem to get it
I'm almost positive you must use 65° instead of 25°, and I have ran out of ways for me to do this problem because I don't know how to get my Intensity because we don't know the Area, so I'm sort of stuck
.2= E(incident) cos (65)
E(incident)= .473 ---> wrong






Thanks!

 

[Doc Al]

Power and intensity are proportional, so just use your first equation (Malus's law).