Figure 10.5 shown a two-slit arrangement with a source which emits unpolarised light. P is a polarizer with axis whose direction is not given. If I₀ is the intensity of the principal maxima when no polarizer is present, calculate in the present case, the intensity of the principal maxima as well as of the first minima.

Question

Philoid · Accepted Answer

Let A_|| denote amplitude of parallel polarization A_⊥ denote amplitude of perpendicular polarization.

Hence, resultant amplitude A is

Without P,

where A¹ and A² are amplitude of two beams.

Now,

Intensity, I

With P, is blocked, then the intensity is given by

Given, (intensity without polariser at principal maxima)

Now,

i.e.,

Intensity at principal maxima with polariser is

Intensity at first minima with polariser is