A linearly polarized electromagnetic wave is sent through two sheets of polarizing material. The first sheet,A, is oriented so that its transmission axis makes an angle of 30deg with respect to the incident electric field of the wave. The second sheet,B, is oriented so that its transmission axis makes an angle of 90deg with the incident electric field of the wave. The incident beam has an electric field of peak magnitude Esubscript0 and average intensity Ssubscript0.
a) What is the peak value of the electric field amplitude after it goes through sheet A?
b) What is the average intensity of the wave after it passes through A?
c) What is the average intensity of the wave after it passes through B?
d) Suppose that A and B are interchanged so that the wave is first incident upon B. What is the average wave intensity after passing through both polarizing sheets?
2007-11-13 12:18:51 · 1 answers · asked by Steph C 1 in Science & Mathematics ➔ Physics
the first polarizer passes light parallel to the axis of the polarizer. THis is the projection of the incident E field on the polarizer's axis.
Ea = E0*cos(30) = sqrt(3)/2*E0
The intensity is the square of the E field: Ia = Ea^2 = 3/4*E0^2
Now Ea is at an angle of 60 deg with respect to polarizer B so the field passing through is:
Eb = Ea*cos(60) =1/2*Ea =sqrt(3)/4*E0
Average intensity is Ib = 3/16*E0
If A and B are interchanged no light passes through. Polarizer B is perpendicular to the incoming light wave and soes not pass it.
2007-11-13 12:31:42 · answer #1 · answered by nyphdinmd 7 · 1⤊ 0⤋