InterviewSolution
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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.
| 1. |
A wave of light having frequency `4 xx 10^(14)`Hz. And speed of light `3 xx 10^8` m/s enters glass of R.I. 1.5. Change in wavelength isA. `2.5 xx 10^(-7) m`B. `2.5 xx 10^(-6) m`C. `2.5 xx 10^(-8)m`D. `2.5 xx 10^(-9)m` |
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Answer» Correct Answer - A `lambda_(a) = (v_(a))/(n) = (3 xx 10^(8))/(4 xx 10^(14)) = 0.75 xx 10^(-6)` `= 7500 Å` `lambda_(g) = (lambda_(a))/(mu_(g)) = (7500)/(1.5) = 5000Å` `lambda_(a) - lambda_(g) = 7500 - 5000 = 2500 Å` |
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| 2. |
The change in wavelenght of light of frequency `4 xx 10 ^(14)`Hz. When it pass from air to glass, is `( mu_("glass") = 1.5)`A. 2500 ÅB. 3500 ÅC. 3000 ÅD. 2000 Å |
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Answer» Correct Answer - A `lambda_(a) = (v_(a))/(n) = (3 xx 10^(8))/(4 xx 10^(14)) = 0.75 xx 10^(-6) = 7500 Å` `lambda_(g) = (lambda_(g))/(mu_(g)) = (7500)/(1.5) = 5000 Å` `lambda_(a) - lambda_(g) = 7500 - 5000 = 2500 Å` |
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| 3. |
If `._(i)mu_(j)` represents refractive index when a light ray goes from mefium `i` to medium `j`, then the product `._(2)mu_(1)xx._(3)mu_(2)xx._(4)mu_(3)` is equal toA. `._(3)mu_(1)`B. `._(3)mu_(2)`C. `._(4)mu_(1)`D. `._(4)mu_(2)` |
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Answer» Correct Answer - C `._(2)mu_(1) xx ._(3)mu_(2) xx ._(4)mu_(3) = (mu_(1))/(mu_(2)) xx (mu_(2))/(mu_(3)) xx (mu_(3))/(mu_(4))` `= (mu_(1))/(mu_(4))` `= ._(4)mu_(1)` |
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| 4. |
When a man and plane mirror both move towards each other at the rate of 10 m/s. At what rate the image approach the man ?A. 10 m/sB. 20 m/sC. 30 m/sD. 40 m/s |
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Answer» Correct Answer - C When a person moves towards a mirror with velocity v, his image approaches the mirror with the same velocity v and the image approaches the person with a velocity 3v. Thus, velocity of image `= 3v = 3 xx 10 = 30 m//s` |
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| 5. |
A plane mirrorr is approaching you at a speed of `10cm//sec`.You can see your image in it. At what speed will your image approach youA. 10 cm/secB. 5 cm/secC. 20 cm/secD. 15 cm/sec |
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Answer» Correct Answer - C In one second distance of mirror is 10 cm and so is the distance of image from the mirror. Hence, distance between object and his image is 20 cm in one second. |
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| 6. |
The wavelength of green light in air and in glass is 5300 Å and 3533 Å. The refractive index of glass isA. 1B. `1.5`C. 2D. `2.4` |
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Answer» Correct Answer - B `mu = (lambda_(a))/(lambda_(g)) = (5300)/(3533) = 1.5` |
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| 7. |
Which of the following is used to eliminate head light glare in automobiles ?A. PolaroidsB. Nicol prismC. Calcite crystalD. Plane mirror |
| Answer» Correct Answer - A | |
| 8. |
We can see object due toA. reflection of light from itB. refraction of light through itC. diffractionD. interference of light |
| Answer» Correct Answer - A | |
| 9. |
A driver can be see the sunset at an angle ofA. `sin^(-1) (4//3)`B. `sin^(-1) (1//3)`C. `sin^(-1) (1//4)`D. `sin^(-1) (3//4)` |
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Answer» Correct Answer - D `mu_(w) = (4)/(5), c = ?` `._(w)mu_(a) = (1)/(._(a)mu_(w)) = sin c` `:. sin c = (1)/((4)/(3)) = (3)/(4)` `c = sin^(-1)((3)/(4))`. |
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| 10. |
One cannot cannot see through fog, becauseA. fog absorbs lightB. light is scattered by the droplets in fogC. light suffers total reflection at the droplets in fogD. the refractive index of fog is infinity |
| Answer» Correct Answer - B | |
| 11. |
Find the velocity of light in water, if its velocity in glass of refractive index 1.5 is `2 xx 10^(8)m//s`. The refractive index of water is 1.33.A. `1.25 xx 10^(8)m//s`B. `2.20 xx 10^(8) m//s`C. `2.15 xx 10^(8)m//s`D. `2.25 xx 10^(8) m//s` |
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Answer» Correct Answer - D `v_(w) = (mu_(g))/(mu_(w))v_(g) = (1.5 xx 2 xx 10^(8))/(1.33) = 2.25 xx 10^(8) m//s` |
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| 12. |
The refractive index of water is 1.33. What will be the speed of light in waterA. `1.33 xx 10^(8) m//s`B. `2.25 xx 10^(8) m//s`C. `3 xx 10^(8) m//s`D. `4 xx 10^(8) m//s` |
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Answer» Correct Answer - B `v_(w) = (v_(a))/(mu_(w)) = (3 xx 10^(8))/(1.33) = 2.25 xx 10^(8) m//s` |
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| 13. |
The correct curve between refractive index `mu` and wavelength `lambda` will be A. AB. BC. CD. D |
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Answer» Correct Answer - A As `lambda` increases, `mu` decrease. Curve A is correct. |
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| 14. |
The ratio of velocities of light in glass to that in water is (refractive index of glass = 1.5 and refactive index of water = 1.33)A. 0.6803 : 1B. 0.4989 : 1C. 0.8867 : 1D. 0.2505 : 1 |
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Answer» Correct Answer - C `(v_(g))/(v_(w)) = ? mu_(g) = 1.5, mu_(w) = 1.33` `(v_(g))/(v_(w)) = (mu_(w))/(mu_(g)) = (1.33)/(1.5) = 0.8867` |
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| 15. |
A prism of refracting angle `60^(@)` is made with a material of refractive index `mu`. For a certain wavelength of light, the angle of minimum deviation is `30^(@)`. For this, wavelength the value of refractive index of the material isA. `1.820`B. 1.503C. 1.414D. 1.231 |
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Answer» Correct Answer - C `A = 60^(@), delta_(m) = 30^(@), mu = ?` `mu = (sin((A+delta_(m))/(2)))/(sin((A)/(2))) = (sin((60+30)/(2)))/(sin((60)/(2)))` `= (sin 45)/(sin 30) = sqrt(2) = 1.414` |
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| 16. |
Unpolarised light of intensity `32 Wm^(-2)` passes through three polarizer such that the transmission axis of the last polarizer is crossed with that of the first. The intensity of final emerging light is `3Wm^(-2)`. The intensity of light transmitted by first polarizer will beA. `32 Wm^(-2)`B. `16 Wm^(-2)`C. `8 Wm^(-2)`D. `4 Wm^(-2)` |
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Answer» Correct Answer - B Intensity of light transmitted by first is half of intensity of unpolarised light `= 16 W//m^(2)`. |
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| 17. |
The wavefront originating from the point source of light at finite distance isA. spherical wavefrontB. plane wavefrontC. cylindrical wavefrontD. circular wavefront |
| Answer» Correct Answer - A | |
| 18. |
In the context of Doppler effect in light, the term red shift signifiesA. decrease in frequencyB. increase in frequencyC. decrease in intensityD. increase in intensity |
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Answer» Correct Answer - A When source moves away from the observer, frequency observed is smaller than that emitted from the source and (as if light emitted is yellow, it will be observed red), this shift is called red shift. |
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| 19. |
Doppler effect for light is usedA. measurement of velocities of distant galaxiesB. to measure speed of rotation of sunC. to measure plasma temperatureD. all of these |
| Answer» Correct Answer - D | |
| 20. |
The Doppler effect can be observed in the following case(s) :A. in the shift of frequency in the light from the two sides of the sun due to rotationB. in the red shift galaxiesC. in the use of radarD. all of these |
| Answer» Correct Answer - D | |
| 21. |
Doppler effect independent ofA. distance of sourceB. velocity of sourceC. velocity of listenerD. none of these |
| Answer» Correct Answer - A | |
| 22. |
Due to Doppler effect, a wavelength in the middle of the visible spectrum will be shifted towards blue whenA. source and observer move away from each otherB. source and observer more towards each otherC. source and observer are at restD. none of these |
| Answer» Correct Answer - B | |
| 23. |
Due to Doppler effect, a wavelength in the middle of the visible spectrum will be shifted towards red whenA. source and observer move away from each otherB. source and observer more towards each otherC. source and observer are at restD. none of these |
| Answer» Correct Answer - A | |
| 24. |
The nature of visible light waves is similar toA. gamma raysB. cathode raysC. `beta`-raysD. alpha rays |
| Answer» Correct Answer - A | |
| 25. |
Light waves are transverse in nature. This is indicated byA. polarisation of lightB. interference of lightC. disperson of lightD. photoelectric effect |
| Answer» Correct Answer - A | |
| 26. |
By corpuscular theory of light, the phenomenon which cannot be explained isA. refractionB. interferenceC. diffractionD. polarisation |
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Answer» Correct Answer - A Corpuscular theory says that light consists of massless particles called corpusules. It travels with speed of light and follows laws of mechanics. This theory explains reflection and refraction by applying conservation laws. |
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| 27. |
If light travels from vacuum to water, its wavelengthA. increasesB. remains constantC. decreasesD. may increases or decreases |
| Answer» Correct Answer - C | |
| 28. |
The nature of light waves is similar toA. alpha raysB. gamma raysC. cathode raysD. cosmic rays |
| Answer» Correct Answer - B | |
| 29. |
The phenomenon of interference is shown byA. only longitudinal mechanical wavesB. only transverse mechanical wavesC. only electromagnetic wavesD. All of the above |
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Answer» Correct Answer - D The Phenomenon of interference of light is shown by all types of waves. As light they also exhibit, wave nature. |
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| 30. |
Select the correct option in the following.A. Christian Huygens a contemporary of Newton established the wave theory of light by assuming that light waves were transverseB. Maxwell provided the compelling theoretical evidence that light is transverse waveC. Thomas Young experimentally proved the wave behaviour of light and Huygens assumptionD. All the statements given above, correctly answers the question what is light |
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Answer» Correct Answer - B From the wave equation, Maxwell could calculate the speed of electromagnetic waves in free space and he found that theoretical value was very close to the measured value of speed of light. From this he propounded that light must be an electromagnetic wave. Thus, according to Maxwell, light waves are associated with changing electric and magnetic fields as changing electric field produces a time and space varying magnetic field and a changing magnetic field produces a time and space varying electric field. The changing electric and magnetic fields result in the propagation of electromagnetic waves (or light waves) even in vacuum behaves as transverse wave nature. |
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| 31. |
For a ray of light, which of the following statements holds true?A. A ray is defined as the path of energy propagationB. The wavelength for a ray of light in geometrical optics is assumed to be negligible, standing to zeroC. A ray of light travels in a straight lineD. All of the above |
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Answer» Correct Answer - D A ray is defined as the path of energy propagation in the limit of wavelength tending to zero. It travels in a straight line and defined as the path of energy propagation. |
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| 32. |
A sperical wavefront propagating in a medium changes intoA. circular wavefrontB. cylindrical wavefrontC. plane wavefrontD. elliptical wavefront |
| Answer» Correct Answer - C | |
| 33. |
To form K-polaroid polyvinyl alcohol is heated withA. HClB. `H_(2)SO_(4)`C. NaOHD. `CuSO_(4)` |
| Answer» Correct Answer - A | |
| 34. |
Which of the following polaroid is formed by stretching polyvinyl alcohol by the stress ?A. P-polaroidB. H-polaroidC. K-polaroidD. N-polaroid |
| Answer» Correct Answer - B | |
| 35. |
Which of the following phenomenon is not common to sound and light waves ?A. InterferenceB. DiffractionC. PolarisationD. Reflection |
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Answer» Correct Answer - C Polarisation is not shown by sound waves. |
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| 36. |
The phenomenon of change in path of ray of light when it passes from one medium to another medium isA. reflection of lightB. refraction of lightC. interference of lightD. diffraction of light |
| Answer» Correct Answer - B | |
| 37. |
The phenomenon which does not takes place in sound waves isA. interferenceB. PolarisationC. diffractionD. scattering |
| Answer» Correct Answer - B | |
| 38. |
Which of the following phenomenon is used to test and measure the optical activity of crystal like quartz ?A. InterferenceB. PolarisationC. DiffractionD. Refraction |
| Answer» Correct Answer - B | |
| 39. |
Time taken by sunlight to pass through a window of thickness `4 mm` whose refraactive index is `(3)/(2),` isA. `2 xx 10^(-1) sec`B. `2 xx 10^(8) sec`C. `2 xx 10^(-11) sec`D. `2 xx 10^(11) sec` |
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Answer» Correct Answer - C `v_(m) = (v_(a))/(mu_(m)) = (3 xx 10^(8))/(1.5) = 2 xx 10^(8)m//s` Thus, time `= ("distance")/("velocity") = (4 xx 10^(-3))/(2 xx 10^(8))` `= 2 xx 10^(-11) sec` |
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| 40. |
In case of linearly polarised light, the magnitude of the electric field vectorA. does not change with timeB. varies periodically with timeC. increases and decreases linearly with timeD. is parallel to the direction of propagation |
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Answer» Correct Answer - B Electric field vector is the form of electromagnetic wave, hence it varies periodically with time. |
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| 41. |
Light waves travel in vacuum along the y-axis. Which of the following may represent the wavefront?A. y = constantB. x = constantC. z = constaneD. x + y + z = constant |
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Answer» Correct Answer - A As velocity of light is perpendicular to the wavefront and light is travelling in vacuum along the Y-axis, therefore, the wavefront is represented by y = constant. |
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| 42. |
A beam of natural light falls on a system of 6 polaroids, which are arranged in succession such that each polaroid is turned through `30^@` with respect to the preceding one. The percentage of incident intensity that passes through the system will beA. 1B. 0.5C. 0.3D. 0.12 |
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Answer» Correct Answer - D If n polaroids are arranged in succession such that each is turned through `theta` with respect to preceding then the intensity of `n^(th)` polaroid is `I_(n) = (I_(0))/(2) (cos^(2) theta)^(n-1)` `I_(6) = (I_(0))/(2) (cos^(2) 30)^(5) = (I_(0))/(2) xx (3)/(4)xx (3)/(4)xx (3)/(4)xx (3)/(4)xx (3)/(4)` `(I_(6))/(I_(0)) = (243)/(2048) = 0.1186 ~~ 12%` |
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| 43. |
Our eye is most sensitive for which of following wavelengthA. 4500 ÅB. 5500 ÅC. 6500 ÅD. equally sensitive for all wavelengths of visible spectrum |
| Answer» Correct Answer - B | |
| 44. |
Which of the following is based on the principle of selective absorption ?A. Nicol prismB. PolaroidsC. BiprismD. Plane mirror |
| Answer» Correct Answer - B | |
| 45. |
Which of the following is used to improve the colour contrast in old paitings?A. RectifierB. Nicol prismC. SpectrometerD. Polaroids |
| Answer» Correct Answer - D | |
| 46. |
Which of the following polaroids is developed by Land and Rogger ?A. P-polaroidB. H-polaroidC. K-polaroidD. D-polaroid |
| Answer» Correct Answer - C | |
| 47. |
Blue colour of water in sea is due toA. reflection of light and scattering of light from water particlesB. bottom of sea is blueC. large depth of sea waterD. sea water is saltish |
| Answer» Correct Answer - A | |
| 48. |
Which of the following is an ascending order of frequency ?A. Red, green, yellow, blueB. Blue, green, yellow, redC. Red, yellow, green, blueD. Red, green, blue, yellow |
| Answer» Correct Answer - C | |
| 49. |
The incident ray, the reflected ray and normal to the reflecting surface lie in same plane. This statement isA. first law of reflectionB. second law of reflectionC. third law of reflectionD. none of these |
| Answer» Correct Answer - B | |
| 50. |
The wavelength of light visible to eye is of the order ofA. `10^(-2)`mB. `10^(-10)m`C. 1mD. `6 xx 10^(-7) m` |
| Answer» Correct Answer - D | |