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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.
| 501. |
Dispersive power does not depend uponA. The shape of prismB. Material of prismC. Angle of prismD. Height of the prism |
| Answer» Correct Answer - b | |
| 502. |
When white light passes through the achromatic combination of prisms, then what is observedA. Only deviationB. Only dispersionC. Deviation and dispersionD. None of the above |
| Answer» Correct Answer - a | |
| 503. |
The refractive index of a prism for a monochromatic wave is `sqrt(2)` and its refracting angle is `60^(@)` for minimum deviation, the angle of indidence will beA. `30^(@)`B. `45^(@)`C. `60^(@)`D. `75^(@)` |
| Answer» Correct Answer - b | |
| 504. |
The dispersion for a medium of wavelength `lambda` is D, then the dispersion for the wavelength `2lambda` will beA. `D//8`B. `D//4`C. `D//2`D. D |
| Answer» Correct Answer - a | |
| 505. |
Speed of light is maximum inA. WaterB. AirC. GlassD. Diamond |
| Answer» Correct Answer - b | |
| 506. |
Which one of the following statements is correctA. In vacuum, the speed of light depends upon frequencyB. In vacuum, the speed of light does not depend upon frequencyC. In vacuum, the speed of light is independent of frequency and wavelengthD. In vacuum, the speed of light depends upon wavelength |
| Answer» Correct Answer - c | |
| 507. |
In vacuum the speed of light depends uponA. FrequencyB. Wave lengthC. Velocity of the source of lightD. None of these |
| Answer» Correct Answer - d | |
| 508. |
If the speed of light in vacuum is C m/ sec then the velocity of light in a medium of refractive index 1.5A. Is `1.5 xxC`B. Is CC. Is `C/1.5`D. Can have any velocity |
| Answer» Correct Answer - c | |
| 509. |
A convex mirror is formed from a spherical surface of radius 20 cm. Find the power of the mirror. |
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Answer» Given, radius of curvature, R= 20 cm `therefore` Focal length off the mirror, `f=R/2=20/2=10cm=0.1 m` `therefore` Power of the mirror,`P=1/f=1/0.1=+10 D` |
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| 510. |
An object is 40 cm form a spherical mirror, along the central axis. The image produced is inverted. What is the power of the mirror? |
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Answer» Image is inverted, so it is real, u and v both are negative. Magnification is `(1)/(2)`,therefore,v=`(u)/(2)`. Given, u=-40cm and v=-20 cm Using the mirror formula, `(1)/(v)+(1)/(u)=(1)/(f)` we have, `(1)/(f)=(1)/(-20)-(1)/(40)=(-2-1)/40=(-3)/40` `rArr f=-40/3cm=-40/3xx1/100m=-2/15m` `therefore` Power of the mirror, `P=-1/f=(-1)/(-2/15)=15/2=+7.5 D` |
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| 511. |
Light of wavelength 300 nm in medium A enters into medium B througha plane surface. If frequency of light is `5xx10^(14)` Hz and `v_(a)//v_(b)=4//5`, then find absolute refractive indices of media A and B. |
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Answer» Speed `v_(A)=vlamda_(A)=5xx10^(14)xx300xx10^(-9)=1.5xx10^(8)`m/s Absolute refractive index, `mu_(A)=c/(v_(A))=(3xx10^(8))/(1.5xx10^(8))=2` We have, `muprop1/v` `therefore (mu_(A)/mu_(B))=v_(B)/v_(A) rArr 2/mu_(B)=5/4` Refracticvve index, `mu_(B)=0.8xx2=1.6` |
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| 512. |
If the wavelength of light in vacuum be `lambda`, the wavelength in a medium of refractive index n will beA. `n lambda`B. `lambda/n`C. `lambda/n^(2)`D. `n lambda` |
| Answer» Correct Answer - b | |
| 513. |
(i) Find the speed of light of wavelength `lambda`=780 nm (in air) in a medium of of refractive index µ=1.55. (ii) What is the wave length of this light in the given medium? |
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Answer» (i) Speed of light, v`=c/µ=(3.0xx10^(8))/1.55` `=1.94xx10^(8)` m/s (ii) Wavelength of light in the given medium, `lamda_("medium")=(lamda_(air))/mu=780/1.55=503 nm` |
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| 514. |
What is the cause of the blue colour of ocean ? |
| Answer» Blue colour of ocean is due to preferential scattering of light by water molecules. | |
| 515. |
A compound microscope with an objective of `1.0 cm` focal length and an eye piece of `2.0 cm` focal length has a tube length of `20 cm`. Calculate the magnifying power of microscope is final image is formed at the near point of eye. |
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Answer» Here, `f_0 = 1.0 cm, f_e = 2.0 cm`, `L = 20 cm, d = 25 cm` When final image is formed at the near point of the eye (at least distance `d` of distinct vision), then `m = (L)/(f_0)(1 + (d)/(f_e)) = (20)/(1.0)(1 + (25)/(2)) = 270`. |
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| 516. |
A ray is reflected in turn by three plain mirrors mutually at right angles to each other. The angle between the incident and the reflected rays isA. `90^(@)`B. `60^(@)`C. `180^(@)`D. None of these |
| Answer» Correct Answer - c | |
| 517. |
The length of the compound microscope is `14 cm.` The magnifying power for relaxed eye is `25`. If the focal length of eye lens is `5 cm`, then the object distance for objective lens will beA. `1.8 cm`B. `1.5 cm`C. `2.1 cm`D. `2.4 cm` |
| Answer» Correct Answer - a | |
| 518. |
A corverging lens has a focal length of `20 cm` in air. It is made of a material of refractive index `1.6`. If is immersed in a liquid of refractive index `1.3`, what will be its new focal length ? |
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Answer» Correct Answer - 52 cm Here, `f_a = 20 cm, mu_g = 1.6, mu_l = 1.3, f_l = ?` `(1)/(f_a) = ((mu_g)/(mu_a) - 1) ((1)/(R_1) - (1)/(R_2)) = 0.6 ((1)/(R_1) - (1)/(R_2))` …(i) `(1)/(f_l) = ((mu_g)/(mu_l) - 1) ((1)/(R_1) - (1)/(R_2))` =`((1.6)/(1.3) - 1) ((1)/(R_1) - (1)/(R_2))` ...(ii) Divide (i) by (ii) `(f_l)/(f_a) = (0.6)/(0.3//(1.3)` `f_l = (0.6 xx 1.3 xx 20)/(0.3) = 52 cm`. |
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| 519. |
Two plane mirrors each 1.6 m long, are facing each other. The distance between the mirrors is 20 cm. A light incident on one end of one of the mirrors at an angle of incidence of `30^(@)`. How many times is the ray reflected before it reaches the other end?A. There are 15 reflections counting the first oneB. There are 13 refelections counting the first oneC. There are 12 reflections counting the first oneD. None of the above |
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Answer» (a) From the figure, given in question, `tan30^(2)=(l_(0))/dimpliesl_(0)=d tan 30^(@)=20/(sqrt(3)` `:.` Number of reflections `=[L/(l_(0))]=[(1.6xx100cm)/(20/(sqrt(3))cm)]=14` If first reflection is considered then `n=14+1=15` |
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| 520. |
One a plane mirror, a ray of light is incident at a angle of `30^(@)` with horizontal. To make the reflected ray vertial, at what angle with horizontal must a plane mirror be places? A. `30^(@)`B. `60^(@)`C. `45^(@)`D. `54^(@)` |
| Answer» Correct Answer - (a) | |
| 521. |
A mirror is inclined at an angle of `theta` with horizontal. If a ray of light is incident at an angle of incidence `theta` then the reflected ray makes the following angle with horizontal A. `theta`B. `2theta`C. `(theta)/2`D. none of these |
| Answer» Correct Answer - (d) | |
| 522. |
An equilaterial prism produces a minimum deviation of `30^@`. The angle of incidence is.A. `30^@`B. `60^@`C. `45^@`D. `90^@` |
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Answer» Correct Answer - C For equilaterial prism, `A= 60^@, delta_m = 30^@` As `2 i= A + delta_m = 60^@ + 30^@ = 90^@` `:. i= (90^@)/(2) = 45^@`. |
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| 523. |
For total internal reflection, light must travel |
| Answer» from denser medium , rarer medium. | |
| 524. |
Two plane mirrors are perpendicular to each other. A ray after suffering reflection from the two mirror will beA. perpendicular to the original rayB. parallel to the first rayC. parallel to the first mirrorD. at `45^(@)` to the original ray |
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Answer» (b) Here angular deviation is `delta=2pi-2theta` `=2pi-2xx(pi)/2=pi` Hene final emergent ray is parallel to incident ray. |
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| 525. |
A ray of light falls on a plane mirror. When the mirror is turned, about an axis at right angle to the plane of the mirror through `20^(@)`, the angle between the incident ray and new reflected ray is `45^(@)`. Find the angle between the incident ray and original reflected ray.A. `15^(@)`B. `30^(@)`C. `45^(@)`D. `60^(@)` |
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Answer» (c) When mirror is rotated through an angle `theta` about an axis is the place of mirror, then reflected ray is rotated through an angle `2theta`. When mirror is rotated about an axis perpendicular to the plane of mirror. The angle of incidence and angle of reflection does not change. |
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| 526. |
Two plane mirrors are at right angles to each other. A man stands between them and combs his hair with his right hand. In how many of the images will he be seen using his right handA. NoneB. 1C. 2D. 3 |
| Answer» Correct Answer - b | |
| 527. |
Which is not true for the image formed in a plane mirror ? The image isA. Always realB. Always virtualC. Virtual and laterally invertedD. Real and laterally inverted |
| Answer» Correct Answer - C | |
| 528. |
A plane mirror produces a magnification ofA. `-1`B. `+1`C. ZeroD. Between 0 and +`oo` |
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Answer» Correct Answer - B (b) Sizwe of image formed by a plane mirror, then mirror forms real image, for a virtual object |
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| 529. |
To get three images of a single object, one should have two plane mirrors at an angle ofA. `30^(@)`B. `60^(@)`C. `90^(@)`D. `150^(@)` |
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Answer» Correct Answer - C (c ) As number of images,n=3 So, `n=(360)/(theta)-1` `3=(360)/(theta)-1` `therefore` `theta=90^(@)` |
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| 530. |
The minimum magnifying power of an astronomical telescope is M. If the focal length of its eye-lens is halved, the minimum magnifying power will become:A. `M//2`B. `2M`C. `3M`D. `4 M` |
| Answer» Correct Answer - b | |
| 531. |
In the formation of primary rainbow, the sunlight rays emerge at minimum deviation from rain- drop afterA. One internal reflection and one refractionB. One internal reflection and two refractionsC. Two internal reflections and one refractionD. Two internal reflections and two refractions |
| Answer» Correct Answer - b | |
| 532. |
The relation governing refraction of light from rarer to denser medium at a spherical refracting surface isA. `-(mu_1)/(u)+(mu_2)/(v) = (mu_2 - mu_1)/( R)`B. `(mu_1)/(u)+(mu_2)/(v)=(mu_2 - mu_1)/( R)`C. `(mu_1)/(u)-(mu_2)/(v)=(mu_2 - mu_1)/( R)`D. none of these |
| Answer» Correct Answer - A | |
| 533. |
Which of the following is a correct relationA. `._(a)mu_(r)=._(a)mu_(w)xx._(r)mu_(omega)`B. `._(a)mu_(r)xx._(r)mu_(w)=._(w)mu_(a)`C. `._(a)mu_(r)xx._(r)mu_(a)=0`D. `._(a)mu_(r)//._(w)mu_(r)=._(a)mu_(w)` |
| Answer» Correct Answer - d | |
| 534. |
Which of the following is not a correct statementA. The wavelength of red light is greater than the wavelength of green lightB. The wavelength of blue light is smaller than the wavelength of orange lightC. The frequency of green light is greater than the frequency of blue lightD. The frequency of violet light is greater than the frequency of blue light |
| Answer» Correct Answer - c | |
| 535. |
Wavelength of light in vaccum is 5890 Å, then its wavelength in glass (`mu=1.5`) will beA. 9372 ÅB. 7932 ÅC. 7548 ÅD. 3927 Å |
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Answer» Correct Answer - A (d) Given, wavelength in vaccum = 5890 Å In a medium of refractive index, the wavelength of light decreases to `lamda/mu = 5890/1.5=3927 Å` |
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| 536. |
Missing lines in a continuous spectrum revealA. Defects of the observing instrumentB. Absence of some elements in the light sourceC. Presence in the light source of hot vapours of some elementsD. Presence of cool vapours of some elements around the light source |
| Answer» Correct Answer - d | |
| 537. |
A source emits light of wavelength `4700 Å , 5400 Å` and `6500 Å` . The light passes through red glass before being tested by a spectrometer. Which wavelength is seen in the spectrumA. `6500 Å`B. `5400 Å`C. `4700 Å`D. All the above |
| Answer» Correct Answer - a | |
| 538. |
A turnips sits before a thin coverging lens,outside the focal point of the lens.Teh lens is filled with a transparent gel so that it is flexible by,by squeezing its ends towards its center [as indicated in figure(a)],you can change the curvature of its front and rear sides When you squeeze the lens,the imageA. moves towards the lensB. moves away form the lensC. shifts upD. remains as it is |
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Answer» Correct Answer - A When we squeeze the lens `f`will decrease so turnip will move towards `2f(R )`from `f` so image will move towards lens(from`oorarr2f`) |
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| 539. |
A turnips sits before a thin coverging lens,outside the focal point of the lens.Teh lens is filled with a transparent gel so that it is flexible by,by squeezing its ends towards its center [as indicated in figure(a)],you can change the curvature of its front and rear sides When you squeeze the lens,the lateral height of image.A. increasesB. decreasesC. remains sameD. data insufficient |
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Answer» Correct Answer - B Since Image of object is moving Towards `R` so lateral magnifation will decrease therefore laterial height will decrease. |
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| 540. |
In a compound microscope cross-wires are fixed at the pointA. Where the image is formed by the objectiveB. Where the image is formed by the eye-pieceC. Where the focal point of the objective liesD. Where the focal point of the eye-piece lies |
| Answer» Correct Answer - a | |
| 541. |
In a compound microscope, the focal lengths of two lenses are `1.5 cm` and `6.25 cm` an object is placed at `2 cm` form objective and the final image is formed at `25 cm` from eye lens. The distance between the two lenses isA. `6.00 cm`B. `7.75 cm`C. `9.25 cm`D. `11.00 cm` |
| Answer» Correct Answer - d | |
| 542. |
Where should a person stand straight from the pole of a convex mirror of focal length 2.0 m on its axis, so that the image formed become half of his original height?A. `-2.60 m`B. `-4 .0 m`C. `-0.5 m`D. `-2.0 m` |
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Answer» Correct Answer - D Given, `m=+(1)/(2),f=2 m=200 cm, u = ?` `therefore` Magnification, `m=(f)/((f-u))` `rArr " " +(1)/(2)=(200)/((200-u))` `rArr " " 200-u=400 rArr u=-200 cm` `rArr " " u=-2 m` |
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| 543. |
A convex lens has a focal length of 20 cm. It is used to form an image of an object placed 15 cm from lens. The image isA. virtual inverted and enlargeB. real,inverted and diminishedC. real,inverted and enlargeD. virtual,erect and enlarge |
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Answer» Correct Answer - D When object lies between focs and pole of convex lens, image is virtual, erect and enlarged. |
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| 544. |
A plano convex lens is made of glass of refractive index 1.5. The radius of curvature of its convex surface is R. Its focal length isA. R/2B. RC. 2RD. 1.5R |
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Answer» Correct Answer - C (c ) Focal length of plano- convex lens, `f=R/(µ-1)=R/((15-1))=2R` |
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| 545. |
A plano convex lens is made of glass of refractive index 1.5. The radius of curvature of its convex surface is R. Its focal length isA. R/2B. RC. 2 RD. 1.5 R |
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Answer» Correct Answer - C Focal length of plano-convex lens, `f=(R )/(mu-1)=(R )/((1.5-1))=2R` |
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| 546. |
Resolving power of a telescope will be more, fi the diameter (a) of the objective isA. largerB. smallerC. resolving poer does not depend on aD. None of the above |
| Answer» Correct Answer - (a) | |
| 547. |
The focal length of a double convex lens is equal to radius of curvature of either surface. The refractive index of its material isA. 43526B. 1C. 43558D. none of these |
| Answer» Correct Answer - A | |
| 548. |
One dioptre is the power of a lens of facal lengthA. 1 cmB. 1 mC. `- 1 cm`D. `- 1 m` |
| Answer» Correct Answer - B | |
| 549. |
Refractive index of a medium dependsA. on the medium onlyB. on the incident light onlyC. on both the conditions given in options a and bD. None of the above |
| Answer» (c) Refractive index of a medium depends on the medium as well as on the wavelength of the incident light. | |
| 550. |
A glass piece is dipped in a liquid of refractie index `4//3`, it gets dissappeared in the liquid. The refractive index of the glass piece isA. `3/4`B. `5/3`C. `4/5`D. `4/3` |
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Answer» (d) The glass piece will dissappear only, if the refractive index of the glass and liquid is same. So, refractive index of glass piece must be `4/3`. |
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