8th Class Science Light Question Bank

done Light IIT JEE Objective Problems Total Questions - 27

• question_answer1)
  The number of images of an object placed between two plane mirrors at \[{{45}^{o}}\] to each other is
  A)
   2                                             done clear
  B)
   7      done clear
  C)
   8                             done clear
  D)
   10 done clear
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• question_answer2)
  An object is placed 40 cm in front of a convex mirror of radius of curvature, 20 cm. The image             
  A)
   Is real and 8 cm behind the mirror done clear
  B)
   Is real and 8 cm in front of the mirror done clear
  C)
   Is virtual and 8 cm in front of the mirror done clear
  D)
   Is virtual and 8 cm behind the mirror done clear
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• question_answer3)
  A long vertical pin placed at 40 cm, in front of a concave mirror gives an image at the same position. The focal length of the mirror in meters is
  A)
   0.2 m          done clear
  B)
   0.4 m done clear
  C)
   0.6 m                    done clear
  D)
   0.8 m done clear
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• question_answer4)
  An object 5 cm high is placed at a distance of 15cm from a concave mirror of radius of curvature 20 cm. The height of the image in cm is
  A)
   5 cm                                      done clear
  B)
   20 cm done clear
  C)
   15 cm                   done clear
  D)
   10 cm done clear
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• question_answer5)
  If the object is placed 10 cm in front of a convex mirror of radius of curvature 20 cm, the magnification is
  A)
   2                                             done clear
  B)
   1    done clear
  C)
   1/2   done clear
  D)
   0 done clear
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• question_answer6)
  If a person wants to see his fall size image, the minimum height of a plane mirror should be
  A)
   Two times his height done clear
  B)
   Equal to his height done clear
  C)
   Half his height      done clear
  D)
   One fourth his height done clear
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• question_answer7)
  If the radius of curvature of a concave mirror is R, its focal length is
  A)
   2 R                                         done clear
  B)
   R    done clear
  C)
   R/2        done clear
  D)
   2/R done clear
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• question_answer8)
  A straight stick partially immersed under water obliquely appears to be bent due to
  A)
   Reflection done clear
  B)
   Refraction done clear
  C)
   Total internal reflection done clear
  D)
   Parallax error done clear
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• question_answer9)
  The angle of incidence is the angle made by the incident ray with
  A)
   The surface done clear
  B)
   Normal to the surface done clear
  C)
   The reflected ray done clear
  D)
   The refracted ray done clear
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• question_answer10)
  The refractive index of glass is 1.5 and speed of light in air is\[3\times 1010\text{ }cm/s\], the speed of light in glass is
  A)
   \[4.5\times {{10}^{10}}\text{ }cm/s\]     done clear
  B)
   \[2\times {{10}^{10}}\text{ }cm/s\] done clear
  C)
   \[0.5\times {{10}^{10}}\text{ }cm/s\]     done clear
  D)
   \[1.5\times {{10}^{10}}\text{ }cm/s\] done clear
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• question_answer11)
  Velocity of light in vacuum is
  A)
   \[13\times \text{1}{{\text{0}}^{6}}m/s\]              done clear
  B)
   \[3\times {{10}^{10}}\text{ }m/s\] done clear
  C)
   \[3\times {{10}^{8}}m/s\]                           done clear
  D)
   3 x 105 m/s done clear
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• question_answer12)
  When a light travels from one medium to another medium which are separated by sharp boundary, the characteristic which does not change is
  A)
   Velocity               done clear
  B)
   Wave length done clear
  C)
   Frequency         done clear
  D)
   Amplitude done clear
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• question_answer13)
  A plane mirror reflecting a ray of incident light is rotated through an angle \[\theta \], about an axis through the point of incidence, in the plane of the mirror perpendicular to the plane of incidence. Then (i) The reflected ray does not rotate (ii) The reflected ray rotates through an angle \[\theta \] (iii) The reflected ray rotates through an angle \[2\theta \] (iv) The incident ray is fixed
  A)
   Only (i) is correct done clear
  B)
   (i) and (iii) are correct done clear
  C)
   (iii) and (iv) are correct done clear
  D)
   (ii) and (iv) are correct done clear
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• question_answer14)
  A ray of light is incident on a plane mirror at an angle of incidence of 30°. The deviation produced by the mirror is
  A)
   \[{{30}^{o}}\]                                    done clear
  B)
   \[{{60}^{o}}\]     done clear
  C)
   \[{{90}^{o}}\]                                    done clear
  D)
   \[{{120}^{o}}\] done clear
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• question_answer15)
  If the velocity of light in vacuum is c cm/s, then the velocity of light in a medium of refractive index 1.5 is __
  A)
   1.5 c                                      done clear
  B)
   c done clear
  C)
   c/1.5                     done clear
  D)
   can have any velocity done clear
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• question_answer16)
  The light appears to travel in straight line because
  A)
   It consists of small particles done clear
  B)
   The velocity of light is very large done clear
  C)
   The wavelength of light is very small done clear
  D)
   Light is reflected by surroundings done clear
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• question_answer17)
  The number of images observable between two parallel mirrors is
  A)
   12                                          done clear
  B)
   4 done clear
  C)
   16                                          done clear
  D)
   infinite done clear
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• question_answer18)
  A plane mirror is approaching you at 10 cm per second. You can see your image in it. At what speed will your image approaches you.
  A)
   5 cm/s                  done clear
  B)
   25 cm/s done clear
  C)
   20 cm/s          done clear
  D)
   15 cm/s done clear
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• question_answer19)
  A light bulb is placed between two plane mirrors inclined at an angle of \[{{60}^{o}}.\]The number of images formed are
  A)
   6                                             done clear
  B)
   12     done clear
  C)
   5             done clear
  D)
   4 done clear
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• question_answer20)
  Let the incident ray be fixed. Now, if a plane mirror is rotated through an angle of \[{{20}^{o}}\] about an axis lying in its plane, then the reflected ray turns through an angle
  A)
   \[{{60}^{o}}\]                    done clear
  B)
   \[{{40}^{o}}\] done clear
  C)
   \[{{10}^{o}}\]                                    done clear
  D)
   \[{{30}^{o}}\] done clear
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• question_answer21)
  A clock hung on a wall of a hall has marks instead of numerals on its dial. On the opposite wall, there is a plane mirror and the image of the clock in the mirror indicates the time 7.40. hence, the time on the clock is
  A)
   7.40                       done clear
  B)
   4.20     done clear
  C)
   5.40                       done clear
  D)
   10.7 done clear
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• question_answer22)
  A ray of light that falls on an eye first passes through the
  A)
   pupil                     done clear
  B)
   cornea done clear
  C)
   eye lens             done clear
  D)
   aqueous humour done clear
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• question_answer23)
  The focal length of the eye lens is adjusted by the
  A)
   vitreous humour       done clear
  B)
   aqueous humour done clear
  C)
   ciliary muscles      done clear
  D)
   optic nerves done clear
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• question_answer24)
  The ciliary muscles of the human eye contract and relax in order to
  A)
   adjust the size of the eyeball done clear
  B)
   adjust the focal length of the lens done clear
  C)
   control the amount of light entering the eye done clear
  D)
   prevent foreign elements from entering the eye done clear
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• question_answer25)
  Tina has a defect in her eyes. She is not able to contract her iris properly. As a result of the defect in her eyes, Tina will not be able to see
  A)
   in dim light       done clear
  B)
   near objects done clear
  C)
   in bright light                     done clear
  D)
   distant objects done clear
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• question_answer26)
  The image formed by the eye lens on the retina is
  A)
   real, inverted, and large done clear
  B)
   virtual, erect, and large done clear
  C)
   real, inverted, and diminished done clear
  D)
   virtual, erect, and diminished done clear
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• question_answer27)
  Myopia is a defect of vision caused by
  A)
   a decrease in the retinal distance from the lens done clear
  B)
   a decrease in the diameter of the eyeball done clear
  C)
   an increase in the thickness of the lens done clear
  D)
   an increase in the curvature of the lens done clear
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