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. (dD), (a), , Figure 56, , Now place the two polaroids P and A such that their pass axes are perpendicular to each other [Figure 56 B]. When, cxtjudt light is incident on th sid P. it is found that the intensity of the light transmitted by the polaroid A is zero., , Conclusion. From this experiment, it is concluded that, , ft (i) when ordinary light (i.e. unpolarised light) is incident on the polaroid P, the electric vector vibrating parallel to 2 fae, of the polaroid P passes through it, while the electric vector vibrating perpendicular to the pass-axis of polaroid iS a 2 o ., light transmitted through the polaroid P has only electric vector parallel to its axes. Thus, the polaroid P has restricted . 2 =, of light (electric vector) in one direction. Polaroid P is called polariser and the phenomenon of restricting the vibration 0 | : ;, direction is called polarisation of light. Since the vibrations of light is restricted in a plane, SO the light at : :, polaroid is known as plane polarised light. ‘The intensity of the plane polarised light is half the intensity of the unpolarised light., , (ii) When the pass-axis of the polaroid A is parallel to the direction of the vibrations of the plane polarised light [Figure 56 (a)],, this plane polarised light is transmitted as such by the polaroid A., , (iii) When the pass-axis of the polaroid A is perpendicular to the direction of vibrations of the plane ee =, [Figure 56 (b)], then the vibrations of the plane polarised light is completely blocked. Thus, there is no light transmitted a ;, polaroid A and hence the intensity of light transmitted is zero. The polaroid A identifies the polarisation of light and henc, is known as analyser. This experiment further shows that the light ts transverse in nature., , ann ae a a ener ITS:, Sra gestae se Leumercenears aa, , 5. It, used for n, , 6. Po, , tT. VoD, which are, , 8. L.C, uses the pr, , 9. Pol, discs in C], , 9.7.4, , LL esrsiss, , — 48. Ste, , This k, Of the ano]
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Blasses is less intense. Figure 57 sh, , - 47 AMI CUONS OF Polaroids., , Hlaroids have variety oPyses in a daily life., , {, In Sun glasses (goggles). The light reflected from the bright surfaces such as polished tables, , MM Ordinary 1 light <E Glare highly, reduced, Partially. (> Oil spilled, on road, , , , solarised, , direct light, having same, are, Action of polarised glasses, , Figure 57, , "Wet roads and snow produces glare (i.e. to shine with strong light) in the eyes. This glare is harmful to the eyes and can be, , avoided by wearing sun glasses made of polaroids with vertical transmission axis. The light after passing through such sun, ows the glare produced by reflection of light from top surface of oil, , led on road. This glare is bldgked by the polariser., , _/n trains and aero /Polaroids are used as, *Ppordrold can be rotated to-have-the-desired ip ensity of light., , 0 etdearetrsed_tc eliminate the dazzle from the head list, mensional moving pictures an\, , windows in train and aeroplanes. One of the polaroids is fixed while the, , , , , , , , , , , also used in photographic cameras.
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No, , gure 56 B]. When, id A is zero., , illel to the pass-axis, d is blocked. So the, ricted the vibrations, ation of light in one, transmitted by the, unpolarised light., , ght [Figure 56 (@)]., , ‘ transmitted by the, f light and hence it, , , , , , , , Polaroid, Glasses, , Viewing 3D picture, , Cri, , Deet TUl tia’ fratromt es pol FESLUILS., , 6. Polaroids are used in photo elastic stress4, 7. The microscopes fitted with polaroids enable us to see very, , it is also used in solar compass where polarisation of, , which are otherwise not seen properly due to the glare of light., , 8. L.C.D. i.e. liquid crystal display, uses the principle of polarisation to form num, , 9. Polarised laser beams are used a, , J, , discs oe rs ff, et WLS per yers., , 9.7.4. Malus’_Law, , (Oe, , , , , , ry P / }, alus' law., , a,, , f This law states that the intensity of the po, the angle between the plane of transmission of, , larised light tra, , in calculators, watches, TV,, bers, letters and pictures., , s needles for producing soun, , , , the analyser an, , scattered sunlight is, , €. photo-elasticity analysis., , nsmitt, , , , minute particles, computers etc., , d from compact, , ed through the analyser varies as the sq, d the plane of the polariser., , , , , , , uare of the cosine
