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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 301. |
A diffraction grating has `1.26xx10^(4)` rulings uniformly spaced over width w=25.4 mm. It is illuminated at normal incidence by blue light of wavelength 450 nm At what angles to the central axis do the second order maxima occur |
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Answer» The grafting spacing d is `d=w/N=(25.4xx10^(-3))/(1.26xx10^(4))=20.16xx10^(-6)m=2016nm` The second order maxima corresponds to `n=2` For `lambda=450nm` we have `d sin theta=2lambda rArr theta=sin^(-1)((2lambda)/d)` `rArrtheta=sin^(-1)((2xx450xx10^(-9))/(2.016xx10^(-6)))` `:.Angle theta approx 27^(@)` |
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| 302. |
According to corpuscular theory of light, the different colours of light are due toA. different electromagnetic wavesB. different force of attraction among the corpusclesC. different size of the corpusclesD. None of the above |
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Answer» Correct Answer - C According to corpuscular theory of light, the different colours of light are due to different size of the corpuscles |
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| 303. |
Assertion: A famous painting was painted by not using brush strokes in the usual manner, but rather a myriad of small colour dots. In this painting the colour you see at any given place on the painting changes as you move away. Reason: The angular separation of adjacent dots changes with the distance from the painting.A. (a) If both the assertion and reason are true and reason explains the assertion assertion.B. (b) If both assertion and reason are true but reason does not explain the assertionC. (c) If assertion is true but reason is false.D. (d) If assertion is false but reason is true. |
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Answer» Correct Answer - A Resolving power `=1.22lambda/d`, where `lambda` is wavelength and d is distance. For the human eye the resolving power or angular separation of objects changes as distance from the object changes. Thus, when we are close to the pointing our eyes can pick out the separate colours of dots. But when we move away from the painting, our eyes blend the dots and we see different colours. |
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| 304. |
Assertion: By roughening the surface of a glass sheet its transparency can be reduced. Reason: Glass sheet with rough surface absorbs more light.A. (a) If both the assertion and reason are true and reason explains the assertion assertion.B. (b) If both assertion and reason are true but reason does not explain the assertionC. (c) If assertion is true but reason is false.D. (d) If assertion is false but reason is true. |
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Answer» Correct Answer - C When glass surface is made rough then the light falling on it is scattered in different directions reducing its transparency. Also since rough surfaces scatter light more, it is absorbed less. |
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| 305. |
Two coherent monochromatic light beam of intensitites `I` and`4I` are superposed.The maximum and minimum possible intensities in the resulting beam, isA. `5Iand I`B. `5I and3I`C. `9I and I`D. `9I and 3I` |
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Answer» Correct Answer - C `I_(r)=I_(1)+I_(2)+2sqrt(I_(1)I_(2))cosphi,` `I_(max)=(sqrt(I_(1))+sqrt(I_(2)))^(2)rArr(sqrt(I_(1))+sqrt(4I))^(2)=9I` `I_(min)=(sqrt(I_(1))-sqrt(I_(2)))^(2) rArr (sqrt(I_(1))+sqrt(4I))^(2) rArr I_(min)=I` |
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| 306. |
When a beam of light wavelength `lambda` is incident on the surface of a liquid at an angle `phi` , the reflected ray in completely polarized. The wavelength og light in the liquid medium isA. `lambda T an phi`B. `(lambda)/(T an phi)`C. `(lambda)/(Cos phi)`D. `(lambda)/(Sin phi)` |
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Answer» Correct Answer - B `mu = tan i, mu_(1) lambda_(1) = mu_(2) lambda_(2)` |
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| 307. |
The contrast in the fringes in any interference pattern depends on:A. Fringe widthB. WavelengthC. Intensity ratio of the sourcesD. Distance between the sources |
| Answer» Correct Answer - C | |
| 308. |
The contrast in the fringes in any interference pattern depends on:A. fringe widthB. wavelengthC. intensity ratio of the sourcesD. distance between the source |
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Answer» Correct Answer - C contrast indicates the ratio of maximum possible intensity on screen to the minima possible intensity. As `(I_(max))/(I_(min))=(sqrt(I_(1))+sqrt(I_(2)))^(2)/((sqrt(I_(1))-sqrt(I_(2)))^(2))` So it only depends on the source intensity |
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| 309. |
The contrast in the fringes in any interference pattern depends on:A. fringe widthB. wave lengthC. intensity ratio of the sourcesD. distance between the sources. |
| Answer» Correct Answer - C | |
| 310. |
If monochromatic red light is replaced by green light the fringe width becomesA. increaseB. remain sameC. we cannot sayD. decrease |
| Answer» Correct Answer - D | |
| 311. |
The diffraction effect can be observed inA. Only sound wavesB. Only light wavesC. Only ultrasonic wavesD. Sound as well as light waves |
| Answer» Correct Answer - D | |
| 312. |
The distance upto which ray optics holds good is calledA. Fresnel distanceB. Fraunhofer distanceC. Optical distanceD. Wave distance |
| Answer» Correct Answer - A | |
| 313. |
Choose the correct statementA. A telescope magnifiesB. A microscope resolvesC. A telescope resolvesD. Both (2) and (3) |
| Answer» Correct Answer - C | |
| 314. |
Huygens wave theory allows us to knowA. The wavelength of the waveB. The velocity of the waveC. The amplitude of the waveD. The propagation of wavefronts |
| Answer» Correct Answer - D | |
| 315. |
Huygens wave theory allows us to knowA. (a) The wavelength of the waveB. (b) The velocity of the waveC. (c) The amplitude of the waveD. (d) The propagation of wavefronts |
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Answer» Correct Answer - D Huygens theory explains propagation of wavefront. |
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| 316. |
The wave theory of light was given byA. (a) MaxwellB. (b) PlanckC. (c) HuygensD. (d) Young |
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Answer» Correct Answer - C Wave theory of light is given by Huygens. |
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| 317. |
The phase difference between incident wave and reflected wave is `180^@` when light rayA. (a) Enters into glass from airB. (b) Enters into air from glassC. (c) Enters into glass from diamondD. (d) Enters into water from glass |
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Answer» Correct Answer - A When light reflect from denser surface phase change or `pi` occurs. |
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| 318. |
Which of the following phenomena can explain quantum nature of light?A. (a) Photoelectric effectB. (b) InterferenceC. (c) DiffractionD. (d) Polarisation |
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Answer» Correct Answer - A Photoelectric effect explain the quantum nature of light while interference, diffraction and polarization explain the wave nature of light. |
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| 319. |
Which of the following is not a property of light?A. (a) It requires a material medium for propagationB. (b) It can travel through vacuumC. (c) It involves transportation of energyD. (d) It has finite speed |
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Answer» Correct Answer - A Light is electromagnetic in nature it does not require any material medium for its propagation. |
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| 320. |
The phenomenon of interference is shown byA. (a) Longitudinal mechanical waves onlyB. (b) Transverse mechanical waves onlyC. (c) Electromagnetic waves onlyD. (d) All the above types of waves |
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Answer» Correct Answer - D Interference is shown by transverse as well as mechanical waves. |
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| 321. |
The energy in the phenomenon of interference-A. is conserved, gets redistributedB. is equal at every pointC. is destroyed in regions of dark fringesD. is created at the place of bright fringes. |
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Answer» Correct Answer - A In interference pattern we can see that resultant amplitude of super imposed wave depends on the phase difference of waves so it varies from maximum to minimum amplitude by redistributing of energy but total energy remains conserved. |
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| 322. |
InterferenceA. transverse nature of lightB. longitudinal nature of lightC. wave nature of lightD. particle nature of light |
| Answer» Correct Answer - C | |
| 323. |
When interference of light takes placeA. energy is created in the region of maximum intensityB. energy is destroyed in the region of maximum intensityC. conservation of energy holds good and energy is radistributedD. conservation of energy does not hold good |
| Answer» Correct Answer - C | |
| 324. |
Two point coherent sources of power `P_(0) nad 4P_(0)` emmitting sound of frequency 150 Hz are kept at point A and B respectively. Both sources are in same phase. A detector is kept at point C as showin in figure. The distance of point A and B is r and 4r form detectro respectively. The speed of sound in medium is 300 m/s . Given `P_(0)=64pi` Watt and r=1m. The intensity observed by detector is A. `25W//m^(2)`B. `4W//m^(2)`C. `9W//m^(2)`D. zero |
| Answer» Correct Answer - B | |
| 325. |
Two coherent light sources, each of wavelength `lambda`, are separated by a distance `3 lambda`, The maximum number of minima formed on line AB, which funs from `-oo` to `+oo`, is A. 2B. 4C. 6D. 8 |
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Answer» Correct Answer - C There can be three minima from central point to corresponding to `(lambda)/2,(3lambda)/2,(5lambda)/2`, path difference `:. ` total number of minima `=2n_(max)=6` |
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| 326. |
Explain why two flashlights held close together do not produce an interference pattern on a distant screen? |
| Answer» The light form the flashlights consists of many different wavelengths (that is why it is white) with random time difference between the light wave, therefore there is no coherence between the two sources, and no possibility of an interference pattern. | |
| 327. |
A thin transparent film of thickness 3000 `Å` and refractive index 1.5 ud deposited on a sheet made of a metal. Assuming normal incidence of light and also that the film is a plane parallel one, what will be the color of a pot made from this sheet when observed in white light? |
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Answer» Coditiions for maximum and minimum intensity in reflected light, in case of thin film interference, are Maxima: `2 mu t = (2n 1) lambda//2, n = 1, 2,…` Minima: `2 mu t = n lambda, n = 0, 1, 2, 3,…` Given: `mu = 1.5 , t = 3000 Å = 3000 xx 10^(10) m` (normal incidence) Maxima: `2 mu t = (2 n - 1) lambda//2` `:. 2 xx 1.5 xx (3000 xx 10^(-10)) = (2n - 1) lambda//2` or `lambda = (4 xx 1.5 xx 3000 xx 10^(-10))/(2n -1)` `:. lambda =(18000)/(2n - 1) xx 10^(-10) m` For `n = 1,lambda = 18000 Å` `n = 2, lambda = 6000 Å` `n = 3, lambda = 3600 Å` and so on Only `lambda = 6000 Å` for `n = 2` lies in the visible range. Intensity will be minimum for `lambda = 4500 Å` which falls in the violet-blue pat of the visible spectrum. When observed in white light, the red -orange part will be strongly reflected and the violet-blue part will be quite reduced in intensity. Hence, Colour of the pot will appear to be orange-red. |
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| 328. |
A soap bubble of µ=4/3 is illuminated by white light incident at an angle of `30^(@)`. The transmittedlight is examined by a spectroscope and bright band is found for a wavelength of 6000 Å. Find the thickness of the film. |
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Answer» Correct Answer - `2.4xx10^(-7)`m |
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| 329. |
Which of the following is conserved when light waves interfereA. momentumB. amplitudeC. energyD. intensity |
| Answer» Correct Answer - C | |
| 330. |
The nessary condition for an interference by two sources of light is that:A. two light sources must have same wavelengthB. two point sources must should have the same amplitude and same wavelengthC. two source should have the same wavelength, nearly the same amplitude and have a constant phase angle differenceD. the point sources should have a randomly varying difference |
| Answer» Correct Answer - C | |
| 331. |
Which of the following is conserved when light waves interfereA. IntensityB. EnergyC. AmplitudeD. Momentum |
| Answer» Correct Answer - B | |
| 332. |
Statement-1: In YDSE, if initial phase difference between waves is `pi`, central maxima will be occupied by minima. Statement-2: In YDSE , if incident light is white light, then central fringe is white while all other fringes are coloured. Statement-3 : A thic transparent liquid film floating upon water, when illuminated by while light, appears coloured.A. FTTB. TTTC. TFFD. TTF |
| Answer» Correct Answer - B | |
| 333. |
For the sustained interference of light, the necessary condition is that the two sources shouldA. Have constant phase differenceB. Be narrowC. Be close to each otherD. Of same amplitude |
| Answer» Correct Answer - A | |
| 334. |
Statement-1: Two separate sources of light giving out light of the same frequency do not produce sustained interference. Statement-2 : The amplitude of the waves from the sources are never equal.A. Statement-1 is true, statement-2 is true, statement-2 is a correct explanation for statement-4B. Statement-1 is true, statement-2 is true, statement-2 is NOT a correct explanation for statement-3C. Statement-1 is true, statement-2 is falseD. Statement-1 is false, statement-2 is true |
| Answer» Correct Answer - C | |
| 335. |
For the sustained interference of light, the necessary condition is that the two sources shouldA. (a) Have constant phase differenceB. (b) Be narrowC. (c) Be close to each otherD. (d) Of same amplitude |
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Answer» Correct Answer - A The essential condition for sustained interference is constancy of phase difference. |
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| 336. |
A thin slice is cut out of a glass cylinder along a plane parallel to its axis. The slice is placed on a flat glass plate as shown in Figure. The observed interference fringes from this combination shall be A. straightB. circularC. equally speedD. having frings spacing which increases as we go outwards. |
| Answer» Correct Answer - A | |
| 337. |
The polarising angle for glass isA. same for different kinds of glassB. different for different kinds of glassC. same for light of all coloursD. varies with time |
| Answer» Correct Answer - B | |
| 338. |
At a finite distance from the source, a point source of light producesA. spherical wave frontB. plane wavefrontC. cylindrical wavefrontD. both sperical and plane wavefronts |
| Answer» Correct Answer - A | |
| 339. |
Transverse wave nature is established byA. InterferenceB. DiffractionC. PolarizationD. All the above |
| Answer» Correct Answer - C | |
| 340. |
Nature of wave front depends onA. shapes of sourceB. distance of sourceC. both 1 and 2D. none of these |
| Answer» Correct Answer - C | |
| 341. |
Wave nature of light follows becauseA. (a) Light rays travel in a straight lineB. (b) Light exhibits the phenomena of reflection and refractionC. (c) Light exhibits the phenomenon of interferenceD. (d) Light causes the phenomenon of photoelectric effect |
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Answer» Correct Answer - C Interference is explained by wave nature of light. |
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| 342. |
Wavefront meansA. (a) All particles in it have same phaseB. (b) All particles have opposite phase of vibrationsC. (c) Few particles are in same phase, rest are in opposite phaseD. (d) None of these |
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Answer» Correct Answer - A Wavefront is the locus of all the particles which vibrates in the same phase. |
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| 343. |
Wavefront meansA. All particles in it have same phaseB. All the particles have opposite phase of vibrationC. Few particles are in same phase, rest are in opposite phaseD. None of these |
| Answer» Correct Answer - A | |
| 344. |
Two coherent source of light can be obtained byA. Two different lampsB. Two different lamps of different powerC. Two different lamps of same powerD. By dividing a wavefront |
| Answer» Correct Answer - D | |
| 345. |
Two sources of waves are called coherent ifA. Both have same amplitude of vibrationB. Both produce waves of same wavelengthC. Both produce waves of the same wavelength having constant phase differenceD. Both produce waves having same velocity |
| Answer» Correct Answer - C | |
| 346. |
White light may be considered to be mixture of waves of `lambda` ranging between `3900 Å` and `7800 Å`. An oil film of thickness `10,000 Å` is examined normally by the reflected light. If `mu=1.4`, then the film appears bright forA. 4308Å=1.4, 5091Å,6222ÅB. 4000Å,5091Å,5600ÅC. 4667Å,6222Å,7000ÅD. 4000Å,4667Å,5600Å,7000Å |
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Answer» Correct Answer - A |
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| 347. |
Two parallel pillars are `11 km` away from an observer. The minimum distance between the pillars so that they can be seen separately will beA. `3m`B. `1m`C. `0.25m`D. `0.5m` |
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Answer» Correct Answer - A Resolving power of eye `= ((1)/(60))^(@)` `(1)/(60)xx(pi)/(180) = (d)/(11000)` |
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| 348. |
Following figures shows sources `S_1` and `S_2` that emits light of wavelength `lambda` in all directions. The sources are exactly in phase and are separated by a distance equal to `1.5lambda`. If we start at the indicated start point and travel along path 1 and 2, the interference produce a maxima all along A. (a) Path 1B. (b) Path 2C. (c) Any pathD. (d) None of these |
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Answer» Correct Answer - A At any point along the path 1, path difference between the wave is 0. Hence maxima is obtained all along the path 1. At any point along the path 2, path difference is `1.5lambda` which is odd multiple of `lambda/2`, so minima is obtained all along the path 2. |
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| 349. |
Two identical light sources `S_1` and `S_2` emit light of same wavelength `lambda`. These light rays will exhibit interference ifA. (a) Their phase differences remain constantB. (b) Their phases are distributed randomlyC. (c) Their light intensities remain constantD. (d) Their light intensities change randomly |
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Answer» Correct Answer - A For interference phase difference must be constant. |
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| 350. |
The velocity of light in air is `3xx10^(8)ms^(-1)` and that in water is `2.2xx10^(8)ms^(-1).` Find the polrising an gle of incidence.A. `45^(@)`B. `50^(@)`C. `53.74^(@)`D. `63^(@)` |
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Answer» Correct Answer - C The refractive index of water `mu=("speed of light in air")/("speed of light in water")=(3xx10^(8))/(2.2xx10^(8)=1.36` From Brewsters law, ` "tan" i_(p)=mu=1.36` ` :. i_(p)="tan"^(-1)(1.36)=53.74^(@)` |
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