Unpolarized light of initial intensity 26.0 W/m^2 is passed through three polari

Question

Unpolarized light of initial intensity 26.0 W/m^2 is passed through three polarizing filters. Viewed in the direction the light is travelling, the axis of the first polarizing filter is vertical, the axis of the second polarizing filter is at 35.0 degree clockwise from the vertical, and the axis of the third polarizing filter is at 75.0 degree clockwise from the vertical. What is the intensity of the light after it has passed through all three polarizing filters? b) Sinusoidal electromagnetic waves from a radio station pass perpendicularly through an open window that has area 0.200 m^2. At the window, the magnetic field of the wave has amplitude B_max = 7.00 times 10^-10 T. How much energy does the wave carry through the window in 2.00 minutes?

Explanation / Answer

(A) as unpolarised light passes through polarizer,

I = Io /2
after that

If = I ( cos(theta))^2

If = I0 (1/2) (cos35)^2 (cos(75-35))^2

If = (26/2) (cos35)^2 (cos40)^2

If = 5.12 W/m^2

(B) I = c Bm^2 / 2 u0

I = (3 x 10^8) (7 x 10^-10)^2 / (2 x 4pi x 10^-7)

I = 5.85 x 10^=5 W/m^2

E = I A t

= (5.85 x 10^-5) (0.200) (2 x 60)

= 1.404 x 10^-3 J

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