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| 1. |
How can you detect a polarized light? |
| Answer» <html><body><p></p>Solution :Take two tourmaline <a href="https://interviewquestions.tuteehub.com/tag/crystals-940110" style="font-weight:bold;" target="_blank" title="Click to know more about CRYSTALS">CRYSTALS</a> `T_(1)` and `T_(2)` cut with their <a href="https://interviewquestions.tuteehub.com/tag/faces-982657" style="font-weight:bold;" target="_blank" title="Click to know more about FACES">FACES</a> <a href="https://interviewquestions.tuteehub.com/tag/parallel-1146369" style="font-weight:bold;" target="_blank" title="Click to know more about PARALLEL">PARALLEL</a> to the axis of the crystal. A <a href="https://interviewquestions.tuteehub.com/tag/fine-989069" style="font-weight:bold;" target="_blank" title="Click to know more about FINE">FINE</a> beam of light from the source S is passed through `T_(1)` and light is observed by placing eye behind `T_(2)`. <br/> <img src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/MBD_EM_PHY_XII_C06_E02_034_S01.png" width="80%"/> <br/> When the axis of `T_(1)` and `T_(2)` are parallel, maximum light is observed [Fig. (i)] but when the axis of `T_(1)` and `T_(2)` are crossed (<a href="https://interviewquestions.tuteehub.com/tag/perpendicular-598789" style="font-weight:bold;" target="_blank" title="Click to know more about PERPENDICULAR">PERPENDICULAR</a>), then practically no light is observed. This phenomenon can only be explained if light waves are transverse. Light falling on `T_(1)` has transverse vibrations lying in all possible directions. `T_(1)` allows only vibrations which are parallel to the axis of `T_(1)` . If second crystal `T_(2)` is placed parallel to `T_(1)` as in first figure, then vibrations transmitted by `T_(1)` are also transmitted by `T_(2)`. If `T_(2)` is perpendicular to `T_(1)`, the vibrations from `T_(1)` are perpendicular to the axis of `T_(2)`. Hence `T_(2)` will not allow these vibrations to pass [Fig. (ii)]. <br/> Longitudinal vibrations can however pass through slits irrespective of their orientations. This is the reason as to why the sound waves cannot be polarised. <br/> Due to the change of the intensity of polarised light as a result of relative orientation of their crystallographic axis, it is concluded that the light waves must be transverse in nature.</body></html> | |