InterviewSolution
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InterviewSolution
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Plane-polarized light of wavelength 0.59mu m falls on a trihedral quartz prism P (Fig.) with refracting angle Theta = 30^(@). Inside the prism light propagates along the optical axis whose direction is shwon by hatching. Behind the Polaroid Pol an interference pattern of bright and dark fringes of width Deltax = 15.0mm is pbserved. Find the specific rotation constant of quartz and the distribution of intensity of light behind the Polaroid. |
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Answer» Solution :Plane polarized light on entering the wedge decomposes into right and LEFT circualry polarized light which travel with difference speeds in `P` and the EMERGENT light gets its plane of polarization rotated by an angle which depends on the disatnce travelled. Given that `Delta x =` fringe width `Delta x tan theta =` difference in the path LENGTH traversed by two rays which from successive bright or dark fringes. Thus `(2pi)/(lambda) |n_(R) - n_(1)| Delta x tan theta = 2pi` Thus `alpha = (pi Delta N)/(lambda) = pi//Delta x tan theta` `= 20.8 ang deg//mm` Let `x =` distance on the polaroid Pol as MEASURED from a maximum. Then a ray that falls at this disatnce traverse an extra distance equal to `+- tan theta` and hence a rotation of `+- alphax tan theta = +- (pix)/(Deltax)` VBy malus'law the intensity at this point will be `cos^(2) ((pix)/(Deltax))`. 
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