[{"id":30863,"question":"Two sources of light are said to be coherent when the waves produced by them have","choices":[{"text":"Equal wavelength","value":"A"},{"text":"Equal amplitude","value":"B"},{"text":"Equal wavelength and constant phase difference","value":"C"},{"text":"Amplitude and wavelength are same","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":30862,"question":"If light of low wavelength is used in Young's double slit experiment then width of the fine will","choices":[{"text":"Decreases","value":"A"},{"text":"Increase","value":"B"},{"text":"Not fixed","value":"C"},{"text":"No change","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30861,"question":"Two wave of intensities I an 4I superpose then the maximum and minimum intensities are","choices":[{"text":"5I and 3I","value":"A"},{"text":"9I and I","value":"B"},{"text":"9I and 3I","value":"C"},{"text":"5I and I","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30848,"question":"Which does not show polarization?","choices":[{"text":"Longitudinal waves in gas","value":"A"},{"text":"Transverse wave in gas","value":"B"},{"text":"Both A and B","value":"C"},{"text":"None of these","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30846,"question":"If a lens is cut into two piece perpendicular to the principal axis and only part is used the intensity of the image:","choices":[{"text":"Remains same","value":"A"},{"text":"1/2 times","value":"B"},{"text":"2 times","value":"C"},{"text":"Infinite","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30845,"question":"What is the main cause of the shinning of diamond?","choices":[{"text":"Reflection","value":"A"},{"text":"Refraction","value":"B"},{"text":"Total internal reflection","value":"C"},{"text":"Dispersion of light","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":30844,"question":"Which of the following spectrum have all the frequencies from high to low frequency range?","choices":[{"text":"Band spectrum","value":"A"},{"text":"Continuous spectrum","value":"B"},{"text":"Line spectrum","value":"C"},{"text":"Discontinuous spectrum","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30840,"question":"All of the following statements are correct except","choices":[{"text":"The total focal length of an astronomical telescope is the sum of the focal lengths of its two lenses","value":"A"},{"text":"The image formed by the astronomical telescope is always erect because the effect of the combination of the two lenses is divergent","value":"B"},{"text":"The magnification of an astronomical telescope can be increased by decreasing the focal length of the eyepiece.","value":"C"},{"value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30833,"question":"The length of a telescope is 36 cm.The focal lengths of its lenses can be","choices":[{"text":"30 cm,6 cm","value":"A"},{"text":"-30 cm,-6 cm","value":"B"},{"text":"30 cm,-6 cm","value":"C"},{"text":"-30 cm,-6 cm","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30831,"question":"To increase the magnification of a telescope","choices":[{"text":"The objective lens should be of large focal length and eyepiece should be of short focal length","value":"A"},{"text":"The objective and eyepiece both should be of large focal lengths","value":"B"},{"text":"Both the objective and eyepiece should be of smaller lengths","value":"C"},{"text":"The objective should be small focal length and eyepiece should be of large focal length","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30827,"question":"If tube length of astronomical telescope is 105 cm and magnifying power is 20 for normal setting calculate the focal length of objective","choices":[{"text":"100 cm","value":"A"},{"text":"10 cm","value":"B"},{"text":"20 cm","value":"C"},{"text":"25 cm","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30820,"question":"A planet is observed by an astronomical refracting telescope having an objective of focal length 16 m and an eyepiece of focal length 2 cm.","choices":[{"text":"The distance between the objective and the eyepiece is 8m","value":"A"},{"text":"The angular magnification of the planet is 200","value":"B"},{"text":"The image of the planet is inverted","value":"C"},{"text":"The objective is smaller than the eyepiece","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":30814,"question":"A lens behaves as a converging lens in air and a diverging lens in water the refractive index of the material is","choices":[{"text":"Equal to unity","value":"A"},{"text":"Equal to 1.33","value":"B"},{"text":"Between unity and 1.33","value":"C"},{"text":"Greater than 1.33","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":30810,"question":"An object is placed at a distance of f/2 from a convex lens.The Image will be","choices":[{"text":"At one of the foci,virtual and double its size","value":"A"},{"text":"At,3/f real and inverted","value":"B"},{"text":"At 2f,virtual and erect","value":"C"},{"text":"At f,real and inverted","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30807,"question":"When the length of a microscope tube increases its magnifying power","choices":[{"text":"Decreases","value":"A"},{"text":"Increases","value":"B"},{"text":"Does not change","value":"C"},{"text":"May increase or decrease depending on the observer and the place of observation","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30805,"question":"A converging lens in used to from an image on a screen when the upper half of the lens is covered by an opaque screen","choices":[{"text":"Half the image will disappear","value":"A"},{"text":"No change either in size or in intersity","value":"B"},{"text":"Intensity of image will increase","value":"C"},{"text":"Intensity of the image will decrease","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30804,"question":"A fly is sitting on the objective of a telescope pointed towards the moon.What effect is expected on the photography of the moon taken through the telescope?","choices":[{"text":"The entire field of view blocked","value":"A"},{"text":"There is an image of the fly on the photography","value":"B"},{"text":"There is no effect at all","value":"C"},{"text":"There is a reduction in the intensity of the image","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30803,"question":"For destructive interference the path difference is give by:","choices":[{"text":"(m-1/2)λ","value":"A"},{"text":"(m+1/2)λ","value":"B"},{"text":"mλ","value":"C"},{"text":"1/2 mλ","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30802,"question":"For constructive interference the path difference is","choices":[{"text":"mλ","value":"A"},{"text":"(m-1)λ","value":"B"},{"text":"m<sup>2</sup>λ","value":"C"},{"text":"1/2mλ","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30801,"question":"For interference to occur,the interfering beams of light must be","choices":[{"text":"Of different frequencies","value":"A"},{"text":"Coherent","value":"B"},{"text":"White light","value":"C"},{"text":"Added","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30800,"question":"For interference to occur the two light waves should be:","choices":[{"text":"Of two different frequencies","value":"A"},{"text":"Coming from opposite directions","value":"B"},{"text":"Of high intensity","value":"C"},{"text":"Monochromatic","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30799,"question":"According to Huygen,every point on a wavefront may be regarded as a.........of secondary wavelets.","choices":[{"text":"Base","value":"A"},{"text":"Source","value":"B"},{"text":"Producer","value":"C"},{"text":"Origin","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30797,"question":"The direction of a ray of light is.......to the wave front.","choices":[{"text":"Parallel","value":"A"},{"text":"Equal","value":"B"},{"text":"Opposite","value":"C"},{"text":"Perpendicular","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30794,"question":"Consider telecommunication through optical fibers.Which of the following statements is not true?","choices":[{"text":"Optical fibers may have homogeneous core with a suitable cladding","value":"A"},{"text":"Optical fibers can be of graded refractive index","value":"B"},{"text":"Optical fibers are subject to electromagnetic interference from outside","value":"C"},{"text":"Optical fibers have extremely low transmission loss","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":30791,"question":"In Young's double slit experiment,the separation between the slits is made 3 fold the fringe width becomes","choices":[{"text":"1/3 times","value":"A"},{"text":"1/9 times","value":"B"},{"text":"3 times","value":"C"},{"text":"9 times","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30789,"question":"Optic fibers are related with","choices":[{"text":"Communication","value":"A"},{"text":"Light","value":"B"},{"text":"Computer","value":"C"},{"text":"None of these","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30788,"question":"Sun has elliptical shape when it rises and sets due to","choices":[{"text":"Refraction","value":"A"},{"text":"Reflection","value":"B"},{"text":"Scattering","value":"C"},{"text":"Dispersion","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":30779,"question":"Why laser rays are used to measure long distance?","choices":[{"text":"Laser rays propagate in a straight","value":"A"},{"text":"Laser rays are not absorbed","value":"B"},{"text":"Laser rays are most coherent waves","value":"C"},{"text":"Laser rays are high velocity waves","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30777,"question":"The difference between 1st ring fringe and 1st dark fringe is measured as","choices":[{"text":"λD/2d","value":"A"},{"text":"λD/d","value":"B"},{"text":"λD/4d","value":"C"},{"text":"2λD/d","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30774,"question":"Which is having minimum wavelength?","choices":[{"text":"X-rays","value":"A"},{"text":"Ultra-violet rays","value":"B"},{"text":"Y-rays","value":"C"},{"text":"Cosmic rays","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":30773,"question":"The cause of mirage observed in desert is","choices":[{"text":"Refraction","value":"A"},{"text":"Reflection","value":"B"},{"text":"Scattering","value":"C"},{"text":"Total internal reflection","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30771,"question":"Intensities of the two waves of light are I and 4I.The maximum intensity of the resultant wave after superposition is","choices":[{"text":"5I","value":"A"},{"text":"9I","value":"B"},{"text":"16I","value":"C"},{"text":"25I","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30770,"question":"Fraunhofer's lines commonly visible in the sun's spectrum are examples of","choices":[{"text":"Line emission spectrum","value":"A"},{"text":"Line absorption spectrum","value":"B"},{"text":"Band emission spectrum","value":"C"},{"text":"Band absorption spectrum","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":30768,"question":"On a rainy day if there is an oil drop on tar road colored rings are seen around this drop This is because of","choices":[{"text":"Interference pattern produced due to thin oil film","value":"A"},{"text":"Diffraction pattern","value":"B"},{"text":"Polarization","value":"C"},{"text":"Total internal reflection of light","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30767,"question":"The light produced by a laser is all the following except","choices":[{"text":"Incoherent","value":"A"},{"text":"Monochromatic","value":"B"},{"text":"In the form of a narrow beam","value":"C"},{"text":"Electromagnetic","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30766,"question":"A spectrum which contains all wavelengths without any break is called","choices":[{"text":"Emission spectrum","value":"A"},{"text":"Line spectrum","value":"B"},{"text":"Continuous emission spectrum","value":"C"},{"text":"All of them","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":30765,"question":"In Huygen's wave theory the locus of all points in the same state of vibration is called","choices":[{"text":"A half-period zone","value":"A"},{"text":"Vibrator","value":"B"},{"text":"Wave front","value":"C"},{"text":"A ray","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":30764,"question":"The velocity of light in vacuum can be changed by changing","choices":[{"text":"Frequency","value":"A"},{"text":"Amplitude","value":"B"},{"text":"Wavelength","value":"C"},{"text":"None of these","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":30763,"question":"Choose the correct statement","choices":[{"text":"Rays are normal to wave front","value":"A"},{"text":"Rays may be normal to wave front","value":"B"},{"text":"Rays are not normal to wave front","value":"C"},{"text":"There is no relationship between rays and wave fronts","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":30762,"question":"The splitting of white light into several colors on passing through a glass prism is due to","choices":[{"text":"Refraction","value":"A"},{"text":"Reflection","value":"B"},{"text":"Interference","value":"C"},{"text":"Diffraction","value":"D"},{"value":"E"}],"correctAnswer":1}]