An unpolarized light beam is incident on the polarizer of a polarization experiment and the intensity of light beam emerging from the analyzer is measured as 100 Lumens. Now, if the analyzer is rotated around the horizontal axis (direction of light) by 30° in clockwise direction, the intensity of emerging light will be _________ Lumens.

Concept: 

When an unpolarized light beam is passed through a polarizer then the analyzer

it becomes polarized light with half intensity then its initial value is given as,

⇒  \( I = I_{o} (\cos θ )^{2}\)     ----(1)

where, I_o = intensity of unpolarized light

θ = angle of the polarizer 

I = intensity of light after emerging 

Calculation:

Given: 

The angle between polarizer and analyzer is = 30^o 

The intensity of incident light is I_o  = 100 Lumens

we can write equation (1) as: 

\(I = I_{o} (\cos \theta )^{2}\)  => I = I_o × (cos30)² 

I = 100× \((\frac{\sqrt{3}}{2})^{2} = 3/4\) × 100 = 75 lumens