Answer:
C. 1.5 W/m²
Explanation:
[tex]I_0[/tex] = Unpolarized light = 4 W/m²
[tex]\theta[/tex] = Angle with which the polarizer is turned
The polarization of light is given by
[tex]I=\frac{I_0}{2}cos^2\theta\\\Rightarrow I=\frac{4}{2}cos^2(30)\\\Rightarrow I=2\times \left(\frac{\sqrt3}{2}\right)^2\\\Rightarrow I=1.5\ W/m^2[/tex]
The intensity of light after passing through the first polarizer is 1.5 W/m²