What light intensity emerges from the second filter?

Question

Unpolarized light with intensity 390W/m^2 passes first through a polarizing filter with its axis vertical, then through a polarizing filter with its axis 37 degrees from vertical.

What light intensity emerges from the second filter?

Answer 1

Intensity = Initial Intensity/2 * cos(angle)^2

? = 390/2cos^2(39)

Intensity = 117.8 W/m^2

Unpolarized light that is polarized through a polaroid has half the intensity and the rest of the equation is called Malus' Law.

Answer 2

one half passes through first polarizer.

Answer: 1/2 cos²θ Po