[{"id":30761,"question":"A polarizer is used to","choices":[{"text":"Reduced intensity of light","value":"A"},{"text":"Produce polarized light","value":"B"},{"text":"Increase intensity of light","value":"C"},{"text":"Produce unpolarised light","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30760,"question":"In young's double slit experiment the separation between the slit is halved and distance between the slit and screen is doubled.The fringe width is","choices":[{"text":"Unchanged","value":"A"},{"text":"Halved","value":"B"},{"text":"Doubled","value":"C"},{"text":"Quadrupled","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30759,"question":"Plane microwaves are incident on a long slit having a width of 5 cm.The wavelength of the microwaves if the first minima is formed at 30° is","choices":[{"text":"25 cm","value":"A"},{"text":"5 cm","value":"B"},{"text":"2.5 cm","value":"C"},{"text":"5 mm","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":30758,"question":"Which of the following properties show light is transverse wave in nature?","choices":[{"text":"Interference","value":"A"},{"text":"Reflection","value":"B"},{"text":"Diffraction","value":"C"},{"text":"Polarization","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30757,"question":"To demonstrate the phenomenon of interference we require two sources that emit radiation","choices":[{"text":"Of same frequency","value":"A"},{"text":"Different wavelength","value":"B"},{"text":"Of the same frequency and having definite phase relationship","value":"C"},{"text":"Of nearly the same frequency","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":30756,"question":"The tip of a needle does not give a sharp image it is due to","choices":[{"text":"Polarization","value":"A"},{"text":"Interference","value":"B"},{"text":"Diffraction","value":"C"},{"text":"None of these","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":30755,"question":"Which effect provides direct experimental evidence that light is a transverse rather than a longitudinal wave motion?","choices":[{"text":"Light can be diffracted","value":"A"},{"text":"Two coherent light waves can be made to interfere.","value":"B"},{"text":"The intensity of light from a point source falls off inversely as the square of the distance from the source","value":"C"},{"text":"Light can be polarized","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30754,"question":"Two monochromatic radiations X and Y are incident normally on a diffraction grating.The second order intensity maximum for X coincides with the third order intensity maximum for Y what is the ratio wavelength of X/wavelength of Y?","choices":[{"text":"1/2","value":"A"},{"text":"2/3","value":"B"},{"text":"3/2","value":"C"},{"text":"2/1","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":30753,"question":"Which of the following gives three regions of the electromagnetic spectrum in order of increasing wavelength?","choices":[{"text":"Gamma rays,microwaves,visible radiation","value":"A"},{"text":"Ultraviolet infra-red microwaves","value":"B"},{"text":"Radio waves ultraviolet X-rays","value":"C"},{"text":"Visible radiation gamma rays radio waves","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30752,"question":"Which effect provides direct experiment evidence that light is a transverse rather than a longitudinal,wave motion?","choices":[{"text":"Light can be diffracted","value":"A"},{"text":"Two coherent light waves can be made to be interfere","value":"B"},{"text":"The intensity of light from a point source falls off inversely as the square of the distance from the source","value":"C"},{"text":"Light can be polarized","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30751,"question":"Ultra-violet rays differ from X-rays in that ultra - violet rays","choices":[{"text":"Cannot be diffracted","value":"A"},{"text":"Cannot be polarized","value":"B"},{"text":"Do not affect a photographic plate","value":"C"},{"text":"Have a lower frequency","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":30750,"question":"Which of the following frequency ranges includes most of the electromagnetic waves emitted by the ultra - violet tubes used in a sun bed?","choices":[{"text":"5 x 10<sup>5</sup> to 5 x 10<sup>8</sup> Hz","value":"A"},{"text":"5 x 10<sup>8</sup> to 5 x 10<sup>11</sup> Hz","value":"B"},{"text":"5 x 10<sup>11</sup> to 5 x 10<sup>14</sup> Hz","value":"C"},{"text":"5 x 10<sup>14</sup> to 5 x 10<sup>17</sup> Hz","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30749,"question":"In a spectrometer experiment monochromatic light is incident normally on a diffraction grating having 4.5 x 105 lines per meter.The second order line is seen at an angle of 30 to the normal what is the wavelength of the light?","choices":[{"text":"200 nm","value":"A"},{"text":"430 nm","value":"B"},{"text":"500 nm","value":"C"},{"text":"556 nm","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30748,"question":"In young's slit experiment on interference the ratio of the intensities of a bright band and a dark band is 6 : 1 the ratio of the amplitudes o the interfering waves is","choices":[{"text":"16","value":"A"},{"text":"5/3","value":"B"},{"text":"4","value":"C"},{"text":"1/4","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30747,"question":"Signal from a remote control to the device operated by it travels with the speed of:","choices":[{"text":"Sound","value":"A"},{"text":"Light","value":"B"},{"text":"Ultrasonics","value":"C"},{"text":"Supersonics","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30746,"question":"When the light is incident on polarizing angle which of the following is completely polarized?","choices":[{"text":"Reflected light","value":"A"},{"text":"Refracted light","value":"B"},{"text":"Both reflected and refracted light","value":"C"},{"text":"Neither reflected nor refracted light","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30745,"question":"In the Young's double slit experiment the separation between the slits is halved and the distance between the slits and the screen is doubled the fringe width is","choices":[{"text":"Halved","value":"A"},{"text":"Unchanged","value":"B"},{"text":"Doubled","value":"C"},{"text":"Quadrupled","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30744,"question":"For the sustained interference of light the necessary condition is that the two sources should","choices":[{"text":"Have constant phase difference","value":"A"},{"text":"Be narrow","value":"B"},{"text":"Be close to each other","value":"C"},{"text":"Of same amplitude","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30743,"question":"If a source of light is moving away from stationary observer then frequency of light wave appears to change because of","choices":[{"text":"Doppler's effect","value":"A"},{"text":"Interference","value":"B"},{"text":"Diffraction","value":"C"},{"text":"None of the above","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30742,"question":"When seen in green light the saffron and green portions of our National Flag will appear to be","choices":[{"text":"Black","value":"A"},{"text":"Black and green respectively","value":"B"},{"text":"Green","value":"C"},{"text":"Green and yellow respectively","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30741,"question":"Ray optics is valid,when characteristic dimensions are","choices":[{"text":"Of the same order as the wavelength of light","value":"A"},{"text":"Much smaller than the wavelength of length","value":"B"},{"text":"Of the order of one millimeter","value":"C"},{"text":"Much larger than the wavelength or light","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30740,"question":"When light travels from one medium to another which are separated by a sharp boundary the characteristic which does not change is","choices":[{"text":"Velocity","value":"A"},{"text":"Wavelength","value":"B"},{"text":"Frequency","value":"C"},{"text":"Amplitude","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":30739,"question":"Fraunhofer spectrum is a","choices":[{"text":"Line absorption spectrum","value":"A"},{"text":"Band absorption spectrum","value":"B"},{"text":"Line emission spectrum","value":"C"},{"text":"Band emission spectrum","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30738,"question":"The sky appears blue because","choices":[{"text":"Red light is absorbed","value":"A"},{"text":"Blue light is scattered the most","value":"B"},{"text":"Blue light is absorbed","value":"C"},{"text":"It is its natural color","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30737,"question":"Huygen's wave theory of light cannot explain","choices":[{"text":"Diffraction","value":"A"},{"text":"Interference","value":"B"},{"text":"Polarization","value":"C"},{"text":"Photoelectric effect","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30736,"question":"The contrast in the fringes in any interference pattern depends on","choices":[{"text":"Frings width","value":"A"},{"text":"Intensity ratio of the sources","value":"B"},{"text":"Distance between the slits","value":"C"},{"text":"Wavelength","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30735,"question":"Which one of the following phenomena is not explained by Huygen's construction of wavefront?","choices":[{"text":"Refraction","value":"A"},{"text":"Reflection","value":"B"},{"text":"Diffraction","value":"C"},{"text":"Origin of spectra","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30734,"question":"Light appears to travels in straight lines since","choices":[{"text":"It is not absorbed by the atmosphere","value":"A"},{"text":"It is reflected by the atmosphere","value":"B"},{"text":"Its wavelength is very small","value":"C"},{"text":"Its velocity is very large","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":30733,"question":"The twinkling of stars is due to","choices":[{"text":"The fact that stars do not emit light continususly","value":"A"},{"text":"The refractive index of the earth's atmosphere fluctuate","value":"B"},{"text":"Intermittent absorption of star light by its own atmosphere","value":"C"},{"text":"None of these","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30732,"question":"A prism splits a beam of white light into its seven constituent colors.This is so because","choices":[{"text":"Phase of different colors is diferent","value":"A"},{"text":"Amplitude of different colors is different","value":"B"},{"text":"Energy of different colors is different","value":"C"},{"text":"Velocity of different colors if different","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30731,"question":"A sun rise or sun set the sun looks reddish because","choices":[{"text":"The sun is coldest at these times","value":"A"},{"text":"Of the effects of reflection and refraction","value":"B"},{"text":"The sun is hottest at these times","value":"C"},{"text":"Of the scattering of light","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30729,"question":"One cannot see through fog because","choices":[{"text":"Fog absorbs light","value":"A"},{"text":"The refractive index of fog is infinity","value":"B"},{"text":"Light suffers total reflection at the droplet in a fog","value":"C"},{"text":"Light is scattered by the droplets in fog","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":12069,"question":"Stress beyond which a permanent deformation is observed in a body is called","choices":[{"text":"Minimum stress","value":"A"},{"text":"Maximum","value":"B"},{"text":"Yield stress","value":"C"},{"text":"Plastic stress","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":12065,"question":"Substance which break just after the elastic limit is crossed are called","choices":[{"text":"Soft subtances","value":"A"},{"text":"Hard substances","value":"B"},{"text":"Brittle substances","value":"C"},{"text":"Ductile substances","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":12063,"question":"If stress is increased beyond the elastic limit a permanent change in the material is observed This behavior is called","choices":[{"text":"Elastic deformation","value":"A"},{"text":"Elasticity","value":"B"},{"text":"Plasticity","value":"C"},{"text":"&nbsp;Yield strength","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":12062,"question":"Stress that induces a change in the shape of the body is named as","choices":[{"text":"Tensile stress","value":"A"},{"text":"Volumetric stress","value":"B"},{"text":"Shear stress","value":"C"},{"text":"None of these","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":12061,"question":"Upon applying some unbalanced external stress the deformation may be observed in","choices":[{"text":"Length","value":"A"},{"text":"Surface area","value":"B"},{"text":"Volume","value":"C"},{"text":"All of these","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":12060,"question":"The atoms or molecules in a crystalline solid are held together by","choices":[{"text":"Attractive force","value":"A"},{"text":"Gravitational force","value":"B"},{"text":"Cohesive force","value":"C"},{"text":"Electromagnetic force","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":12059,"question":"The limit below which the Hooke s law holds well is called","choices":[{"text":"Yield point","value":"A"},{"text":"Breaking stress","value":"B"},{"text":"Tensile strength","value":"C"},{"text":"Elastic limit","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":12056,"question":"Steel is more elastic than rubber because","choices":[{"text":"It is a metal","value":"A"},{"text":"Its density is higher","value":"B"},{"text":"Ratio of stress to strain is more","value":"C"},{"text":"Ratio of stress to strain is less","value":"D"},{"value":"E"}],"correctAnswer":3}]