A linearly polarized electromagnetic wave has an average intensity of 392 W/m^2.
ID: 1555798 • Letter: A
Question
A linearly polarized electromagnetic wave has an average intensity of 392 W/m^2. This wave is directed towards two ideal polarizers (In real polarizers, transmission is also effected by reflection and absorption). Polarizer A is oriented with its transmission axis at an angle of theta_1 = 27.2 degree with the incident electric field. Polarizer B has its axis at an angle of theta_2 = 64.2 degree with the incident electric field, as shown in the figure. What is the average intensity of the wave after it passes through polarizer A? What is the average intensity of the wave after it passes through polarizer B? Suppose that the two polarizers A and B are interchanged. What would the average intensity be after passing through both polarizers?Explanation / Answer
Linearly polarized electromagnetic wave has an average intensity,
Io = 392 W/m2
1 = 27.2o
2 = 64.2o
The Average intensity of wave After it passes through polarizer A
According to Malus law,
After passing through polarizer A, the transmitted intensity,
IA = Iocos21
= (392 W/m2)cos2(27.2o)
= 310.09 W/m2
The average intensity of the wave after it passes through polarizer B
After light passes through the second filter, its intensity drops again,
However, its intial intensity is that of the light after passing through filter A
Also the anlge between that which the light travelling and that which it must
pass through an angle : ( 2-1)
Hence,the average intensity of the wave after it passes through polarizer B
IB = IAcos2(2-1)
= (310.09 W/m2)cos2(64.2o - 27.2o)
= 197.78 W/m2
The average intensity of the wave after passing through both polarizers
If filters are interchanged,
The intensity of light after passing through both filters is,
IB = Iocos22
= (392 W/m2)cos2(64.2o )
= 74.25 W/m2
The intensity of light after passing through second filter is,
IA = IBcos2(64.2o - 27.2o)
= (74.25 W/m2)cos2(64.2o - 27.2o)
= 47.35W/m2
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.