[{"id":126329,"question":"Which of the following is an optical fibre in which the density of central core decreases towards its periphery?","choices":[{"text":"multi-mode step index fibre","value":"A"},{"text":"multi-mode graded index fibre","value":"B"},{"text":"both of them","value":"C"},{"text":"none of them","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":126328,"question":"In multi-mode step index optical fibre, that layer is called cladding which has","choices":[{"text":"higher refractive index","value":"A"},{"text":"lower refractive index","value":"B"},{"text":"both of them","value":"C"},{"text":"none of them","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":126327,"question":"The multi-mode step index optical fibre, the central core has","choices":[{"text":"high refractive index and low density","value":"A"},{"text":"low refractive index and density","value":"B"},{"text":"low refractive index and low density","value":"C"},{"text":"high refractive index and high density","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":126323,"question":"Most widely used optical fibres are those which propagate light by","choices":[{"text":"total interval reflection","value":"A"},{"text":"continuous refraction","value":"B"},{"text":"both of them","value":"C"},{"text":"none of them","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":126322,"question":"The light signal in an optical fibre is totally confined due to the","choices":[{"text":"total internal reflection","value":"A"},{"text":"continuous refraction","value":"B"},{"text":"both of them","value":"C"},{"text":"either of them","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":126321,"question":"The light signal in an optical fibre requires that the light should","choices":[{"text":"be partially confined within the fibre","value":"A"},{"text":"be totally confined within the fibre","value":"B"},{"text":"not be confined within the table","value":"C"},{"text":"none of them","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":126320,"question":"Propagation of light in an optical fibre requires that the light should","choices":[{"text":"be partially confined within the fibre","value":"A"},{"text":"be totally confined within the fibre","value":"B"},{"text":"not be confined within the table","value":"C"},{"text":"none of them","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":126318,"question":"The diameter of an optical fibre with its protective case may be typically","choices":[{"text":"7.62 cm","value":"A"},{"text":"67.62 mm","value":"B"},{"text":"6.0 mm","value":"C"},{"text":"90 mm","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":126317,"question":"The information carrying capacity in an optical fibre is called","choices":[{"text":"wavelength","value":"A"},{"text":"frequency","value":"B"},{"text":"bandwidth","value":"C"},{"text":"none of them","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":126316,"question":"For a system to transmit thousands of telephones conversations, several television programs and numerous data signals, it need the following number so threads of optical fibre","choices":[{"text":"100 to 200","value":"A"},{"text":"1000 to 10000","value":"B"},{"text":"100 to 1000","value":"C"},{"text":"1 or 2","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":126315,"question":"Which of the following cannot be polarized?","choices":[{"text":"x-rays","value":"A"},{"text":"light rays","value":"B"},{"text":"sound waves","value":"C"},{"text":"ultraviolet rays","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":126314,"question":"When light passes through a tourmaline crystal, it becomes","choices":[{"text":"plane polarized","value":"A"},{"text":"directly polarized","value":"B"},{"text":"un-polarized","value":"C"},{"text":"spherically polarized","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":126313,"question":"Reflection of light from water, glass, snow and rough road surfaces, for larger angle of incidences, produces","choices":[{"text":"images","value":"A"},{"text":"bright images","value":"B"},{"text":"interference","value":"C"},{"text":"glare","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":126312,"question":"Which of the following phenomenon cannot take place if we consider light as longitudinal wave?","choices":[{"text":"diffraction","value":"A"},{"text":"interference","value":"B"},{"text":"polarization","value":"C"},{"text":"reflection","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":126311,"question":"Which property of waves proves that light is a transverse wave?","choices":[{"text":"diffraction","value":"A"},{"text":"interference","value":"B"},{"text":"polarization","value":"C"},{"text":"reflection","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":126310,"question":"The materials which are used in selective absorption method to polarize the light are","choices":[{"text":"chronic substances","value":"A"},{"text":"organic substances","value":"B"},{"text":"inorganic substances","value":"C"},{"text":"diachronic substance","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":126309,"question":"Which of the following is the most common method to obtain polarized light?","choices":[{"text":"selective absorption","value":"A"},{"text":"reflection from different surfaces","value":"B"},{"text":"refraction through crystals","value":"C"},{"text":"scattering by small particles","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":126308,"question":"If the vibrations of the light wave are confined to one plane only, then this light is called","choices":[{"text":"unpolarized ligth","value":"A"},{"text":"polarized light","value":"B"},{"text":"sunlight","value":"C"},{"text":"none of them","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":126307,"question":"The light which has components in all directions is called","choices":[{"text":"unpolarized light","value":"A"},{"text":"polarized light","value":"B"},{"text":"intense light","value":"C"},{"text":"none of them","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":126306,"question":"Ordinary light has components of vibrations in","choices":[{"text":"one direction only","value":"A"},{"text":"two directions","value":"B"},{"text":"four directions","value":"C"},{"text":"all directions","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":126304,"question":"In light waves, the components of electric and magnetic fields are","choices":[{"text":"parallel to each other","value":"A"},{"text":"anti-parallel to each","value":"B"},{"text":"right angle to each other","value":"C"},{"text":"none of them","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":126303,"question":"A light wave produced by oscillating charge consists of a periodic variation of","choices":[{"text":"electric field","value":"A"},{"text":"magnetic field","value":"B"},{"text":"either of them","value":"C"},{"text":"both of them","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":126301,"question":"The wavelength of light is 6000<span style=\"color: rgb(84, 84, 84); font-family: arial, sans-serif; font-size: small;\">°A, the number of waves continued in 0.01 m distance will be</span>","choices":[{"text":"1.6 x 10<sup>4</sup>","value":"A"},{"text":"3 x 10<sup>3</sup>","value":"B"},{"text":"2 x 10<sup>6</sup>","value":"C"},{"text":"4 x 10<sup>8</sup>","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":126298,"question":"One angshom is equal to?","choices":[{"text":"10<sup>-8</sup>cm","value":"A"},{"text":"10<sup>-6</sup>m","value":"B"},{"text":"10<sup>-10</sup>nm","value":"C"},{"text":"10<sup>-8</sup>nm","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":126297,"question":"Wavelength of X-rays falling at glace angle 30<span style=\"color: rgb(84, 84, 84); font-family: arial, sans-serif; font-size: small;\">° on crystal with atomic spacing 2 x 10<sup>-9</sup>m for the first order diffraction is</span>","choices":[{"text":"4 x 10<sup>-6</sup>m","value":"A"},{"text":"2 x 10<sup>-10</sup>m","value":"B"},{"text":"0.2 x 10<sup>-10</sup>m","value":"C"},{"text":"20 x 10<sup>-10</sup>m","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":126294,"question":"When a mirror of a Michelsion's interferometor is moved a distance of 0.5 mm, 2000 fringes are observed, the wavelength of the light used is","choices":[{"text":"5000 mm","value":"A"},{"text":"5000<span style=\"color: rgb(84, 84, 84); font-family: arial, sans-serif; font-size: small;\">°A</span>","value":"B"},{"text":"500 cm","value":"C"},{"text":"2000<span style=\"color: rgb(84, 84, 84); font-family: arial, sans-serif; font-size: small;\">°A</span>","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":126293,"question":"For the monochromatic beam of X-rays, the crystal planes in a lattice act like a","choices":[{"text":"perfect absorbers","value":"A"},{"text":"boundary","value":"B"},{"text":"mirror","value":"C"},{"text":"none of them","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":126291,"question":"The study of atomic structures of crystals by X-rays was started in","choices":[{"text":"1890","value":"A"},{"text":"1905","value":"B"},{"text":"1914","value":"C"},{"text":"1944","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":126290,"question":"The regular array of atoms in a crystal has spacing of the order of","choices":[{"text":"10<sup>-16</sup>m","value":"A"},{"text":"10<sup>-14</sup>m","value":"B"},{"text":"10<sup>-10</sup>m","value":"C"},{"text":"10<sup>-6 </sup>m","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":126288,"question":"We can observe only when the grating spacing is","choices":[{"text":"of the order of the wavelength used","value":"A"},{"text":"greater than the wavelength used","value":"B"},{"text":"less than the wavelength used","value":"C"},{"text":"any one of them","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":126286,"question":"The wavelength of X-rays is about","choices":[{"text":"10<sup>-14</sup>m","value":"A"},{"text":"10<sup>-10</sup>m","value":"B"},{"text":"10<sup>-6</sup>m","value":"C"},{"text":"10<sup>-4</sup>m","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":126284,"question":"A diffraction grating has 500 liens per mm. its slit spacing or grating element will","choices":[{"text":"500 mm","value":"A"},{"text":"5 x 10<sup>-3 </sup>mm","value":"B"},{"text":"2 x 10<sup>-5</sup>mm","value":"C"},{"text":"2 x 10<sup>-3</sup>mm","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":126282,"question":"If 5000 lines per cm are ruled on different on a diffraction grating then the slit spacing will be","choices":[{"text":"5 x 10<sup>-3</sup>A<span style=\"color: rgb(84, 84, 84); font-family: arial, sans-serif; font-size: small;\">°</span>","value":"A"},{"text":"2 x 10<sup>-4</sup>A<span style=\"color: rgb(84, 84, 84); font-family: arial, sans-serif; font-size: small;\">°</span>","value":"B"},{"text":"5 x 10<sup>-5</sup>A<span style=\"color: rgb(84, 84, 84); font-family: arial, sans-serif; font-size: small;\">°</span>","value":"C"},{"text":"2 x 10<sup>4</sup>A<span style=\"color: rgb(84, 84, 84); font-family: arial, sans-serif; font-size: small;\">°</span>","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":126280,"question":"A diffraction grating contains 5000 lines per centimeter, its grating element will be","choices":[{"text":"1 x 10<sup>-4</sup>nm","value":"A"},{"text":"1 x 10<sup>-14</sup>m","value":"B"},{"text":"1 x 10<sup>-14</sup>cm","value":"C"},{"text":"1 x 10<sup>-4</sup>cm","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":126278,"question":"The diffraction grating is used to measure","choices":[{"text":"wavelength of light","value":"A"},{"text":"focal length of a lens","value":"B"},{"text":"refractive index of prism","value":"C"},{"text":"polarization of light","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":126276,"question":"The spacing between the parallel lines are served as","choices":[{"text":"slits","value":"A"},{"text":"source of light","value":"B"},{"text":"opaque lines","value":"C"},{"text":"fringes","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":126274,"question":"A glass plate on which a large number of very fine equidistant parallel lines are drawn is called","choices":[{"text":"convex lens","value":"A"},{"text":"thin film","value":"B"},{"text":"diffraction grating","value":"C"},{"text":"interferometer","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":126272,"question":"The distance between the top adjacent slits on diffraction grating is called","choices":[{"text":"element","value":"A"},{"text":"grating element","value":"B"},{"text":"aperture","value":"C"},{"text":"slit","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":126270,"question":"A typical diffraction grating has lines per centimeter","choices":[{"text":"10 to 100","value":"A"},{"text":"100 to 1000","value":"B"},{"text":"1000 to 5000","value":"C"},{"text":"400 to 5000","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":126269,"question":"On a diffraction grating which thing acts as a slit","choices":[{"text":"the lines which are ruled on it","value":"A"},{"text":"the spacing between the lines","value":"B"},{"text":"either of them","value":"C"},{"text":"none of them","value":"D"},{"value":"E"}],"correctAnswer":2}]