what is the intensity of the emerging light?

Question

An unpolarized light beam with intensity I₀ is first passed through an ideal polarizer. At this instant, the light is polarized. We then pass that light through 3 more identical polarizers having parallel axes of transmission to each other. If the transmission axis of the final polarizer makes an angle of 45 degrees with the electric field direction of the polarized light, what is the intensity of the emerging light?

a. 0.25

b. 0.25

c. 0.13

d. 0.35

Answer 1

Hi Oscar A.,

Seemingly a hard problem, but not once you master the concepts.

1) unpolarized->polarized = intensity 0.5

2) polarized -> polarized different direction = cos(angle between the polarization direction axes)

= cos (45 degrees) = cos (.pi./4) = 2^0.5/2 So that's 0.35 as a product.

Once the light is polarized, passing through ideal polarizers in the same direction doesn't diminish it at all.

Now here's a though-question for you: ine conceives of the polarizers as always lying perpendicular to the th of the light. But what if one were tilted, either sideways, or to-and-away?

-- Cheers, -- Mr. d.