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- Homework Statement
- Suppose you have a magnetic optical rail with a laser at one end and a lux meter at the other end. You place a polarizer in between. Find a graph of transmitted power ##P_{trans}## vs polarizer angle ##\theta##.

Given that efficiency of the polarizer is given by ##η = \frac{P_{trans}}{P_{max}} =\frac{I_{trans}}{I_{max}}## for when ##\theta = 0##, assume that ##η < 1##

- Relevant Equations
- Malus's law

##I_{trans} = I_{max}(\cos\theta)^2##

##\frac{P_{trans}}{A} = \frac{P_{max}}{A}(\cos\theta)^2## Since ##I = \frac{P}{A}##

##P_{trans} = P_{max}(\cos\theta)^2## (area can be cancelled since we are deriving this equation for one polarizer which we assume to have equal area on each side)

The data collected from the experiment is,

The first column is the polarizer angle measured in degrees.

The second column is recorded intensity measured in lux.

The third column is the transmitted intensity measured in lux. This is equal to the recorded lux - ambient lux

The fourth column is the ambient lux.

I also measured η = 0.543103 (dimensionless)

My confusion is how to find the transmitted power of the laser since the lux meter only reads the transmitted intensity.

So from the definition of power, should we multiply the transmitted intensity by the area of the polarizer? Or should we leave the transmitted power in terms of area A of the polarizer?

Many thanks!

The first column is the polarizer angle measured in degrees.

The second column is recorded intensity measured in lux.

The third column is the transmitted intensity measured in lux. This is equal to the recorded lux - ambient lux

The fourth column is the ambient lux.

I also measured η = 0.543103 (dimensionless)

My confusion is how to find the transmitted power of the laser since the lux meter only reads the transmitted intensity.

So from the definition of power, should we multiply the transmitted intensity by the area of the polarizer? Or should we leave the transmitted power in terms of area A of the polarizer?

Many thanks!

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