JEE Main & Advanced Physics Wave Optics / तरंग प्रकाशिकी Question Bank

done Doppler's Effect of Light Total Questions - 33

• question_answer1)
  The observed wavelength of light coming from a distant galaxy is found to be increased by 0.5% as compared with that coming from a terrestrial source. The galaxy is [MP PMT 1993, 2003]
  A)
             Stationary with respect to the earth done clear
  B)
             Approaching the earth with velocity of light done clear
  C)
             Receding from the earth with the velocity of light done clear
  D)
             Receding from the earth with a velocity equal to \[1.5\times {{10}^{6}}m/s\] done clear
  View Solution play_arrow

• question_answer2)
  A star producing light of wavelength\[6000\,\,{AA}\]moves away from the earth with a  speed of 5 km/sec. Due to Doppler effect the shift in wavelength will be \[(c=3\times {{10}^{8}}m/\sec )\] [MP PMT 1990]
  A)
  \[0.1\,\,{AA}\]                    done clear
  B)
  \[0.05\,\,{AA}\] done clear
  C)
  \[0.2\,\,{AA}\]                    done clear
  D)
  \[1\,\,{AA}\] done clear
  View Solution play_arrow

• question_answer3)
  If the shift of wavelength of light emitted by a star is towards violet, then this shows that star is [RPET 1996; RPMT 1999]
  A)
             Stationary                              done clear
  B)
             Moving towards earth done clear
  C)
             Moving away from earth done clear
  D)
             Information is incomplete done clear
  View Solution play_arrow

• question_answer4)
  Assuming that universe is expanding, if the spectrum of light coming from a star which is going away from earth is tested, then in the wavelength of light
  A)
             There will be no change   done clear
  B)
             The spectrum will move to infrared region done clear
  C)
             The spectrum will seems to shift to ultraviolet side done clear
  D)
             None of the above done clear
  View Solution play_arrow

• question_answer5)
  Doppler's effect in sound in addition to relative velocity between source and observer, also depends while source and observer or both are moving. Doppler Effect in light depend only on the relative velocity of source and observer. The reason of this is                                                  [MP PET/PMT 1988]
  A)
             Einstein mass - energy relation done clear
  B)
             Einstein theory of relativity done clear
  C)
             Photoelectric effect done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer6)
  A rocket is moving away from the earth at a speed of\[6\times {{10}^{7}}m/s\]. The rocket has blue light in it. What will be the wavelength of light recorded by an observer on the earth (wavelength of blue light = \[4600\,{AA}\] )
  A)
  \[4600\,\,{AA}\] done clear
  B)
  \[5520\,\,{AA}\] done clear
  C)
  \[3680\,\,{AA}\] done clear
  D)
  \[3920\,\,{AA}\] done clear
  View Solution play_arrow

• question_answer7)
  A spectral line\[\lambda =5000\,\,{AA}\]in the light coming from a distant star is observed as a\[5200\,\,{AA}\]. What will be recession velocity of the star
  A)
   \[1.15\times {{10}^{7}}cm/\sec \]                                   done clear
  B)
  \[1.15\times {{10}^{7}}m/\sec \] done clear
  C)
  \[1.15\times {{10}^{7}}km/\sec \]                                   done clear
  D)
  1.15 km/sec done clear
  View Solution play_arrow

• question_answer8)
  The apparent wavelength of the light from a star moving away from the earth is 0.01% more than its real wavelength. Then the velocity of star is                                                    [CPMT 1979]
  A)
             60 km/sec                               done clear
  B)
             15 km/sec done clear
  C)
             150 km/sec                            done clear
  D)
             30 km/sec done clear
  View Solution play_arrow

• question_answer9)
  A star emits light of\[5500\,\,{AA}\]wavelength. Its appears blue to an observer on the earth, it means               [DPMT 2002]
  A)
  Star is going away from the earth done clear
  B)
  Star is stationary done clear
  C)
  Star is coming towards earth done clear
  D)
  None of the above done clear
  View Solution play_arrow

• question_answer10)
  The velocity of light emitted by a source S observed by an observer O, who is at rest with respect to S is c. If the observer moves towards S with velocity v, the velocity of light as observed will be                                              [NCERT 1980]
  A)
             c + v                                          done clear
  B)
             \[c-v\] done clear
  C)
             c      done clear
  D)
             \[\sqrt{1-\frac{{{v}^{2}}}{{{c}^{2}}}}\] done clear
  View Solution play_arrow

• question_answer11)
  In the context of Doppler effect in light, the term ?red shift? signifies                                       [MP PET 1994]
  A)
             Decrease in frequency done clear
  B)
             Increase in frequency       done clear
  C)
             Decrease in intensity done clear
  D)
             Increase in intensity done clear
  View Solution play_arrow

• question_answer12)
  The sun is rotating about its own axis. The spectral lines emitted from the two ends of its equator, for an observer on the earth, will show                                                         [MP PMT 1994]
  A)
             Shift towards red end done clear
  B)
             Shift towards violet end done clear
  C)
             Shift towards red end by one line and towards violet end by other done clear
  D)
             No shift done clear
  View Solution play_arrow

• question_answer13)
  A star is moving away from the earth with a velocity of 100 km/s. If the velocity of light is \[3\times {{10}^{8}}m/s\] then the shift of its spectral line of wavelength\[5700\,\,{AA}\]due to Doppler's effect will be                                     [MP PMT 1994]
  A)
  \[0.63\,\,{AA}\]                 done clear
  B)
  \[1.90\,\,{AA}\] done clear
  C)
  \[3.80\,\,{AA}\] done clear
  D)
  \[5.70\,\,{AA}\] done clear
  View Solution play_arrow

• question_answer14)
  If a source of light is moving away from a stationary observer, then the frequency of light wave appears to change because of                                                                  [AFMC 1995]
  A)
             Doppler's effect                  done clear
  B)
             Interference done clear
  C)
             Diffraction                              done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer15)
   A star emitting radiation at a wavelength of \[5000\,{AA}\] is approaching earth with a velocity of\[1.5\times {{10}^{6}}m/s\]. The change in wavelength of the radiation as received on the earth, is                                            [CBSE PMT 1995]
  A)
  \[25\,\,{AA}\] done clear
  B)
  Zero done clear
  C)
  \[100\,\,{AA}\]                   done clear
  D)
  \[2.5\,\,{AA}\]            done clear
  View Solution play_arrow

• question_answer16)
  A star emitting light of wavelength\[5896\,\,{AA}\]is moving away from the earth with a speed of 3600 km / sec. The wavelength of light observed on earth will [MP PET 1995, 2002]
  A)
  Decrease by\[5825.25\,\,{AA}\] done clear
  B)
  Increase by\[5966.75\,\,{AA}\] done clear
  C)
  Decrease by\[70.75\,\,{AA}\] done clear
  D)
  Increase by \[70.75\,\,{AA}\] (\[c=3\times {{10}^{8}}m/\sec \]is the speed of light) done clear
  View Solution play_arrow

• question_answer17)
  A star moves away from earth at speed 0.8 c while emitting light of frequency\[6\times {{10}^{14}}Hz\]. What frequency will be observed on the earth (in units of 1014 Hz) (c = speed of light)                                       [MP PMT 1995]
  A)
             0.24                                           done clear
  B)
             1.2 done clear
  C)
             30   done clear
  D)
             3.3 done clear
  View Solution play_arrow

• question_answer18)
  A light source approaches the observer with velocity 0.8 c. The doppler shift for the light of wavelength \[5500\,{AA}\] is  [MP PET 1996]
  A)
  \[4400\,\,{AA}\]                done clear
  B)
  \[1833\,\,{AA}\] done clear
  C)
  \[3167\,\,{AA}\] done clear
  D)
  \[7333\,\,{AA}\] done clear
  View Solution play_arrow

• question_answer19)
  Light coming from a star is observed to have a wavelength of 3737 Å, while its real wavelength is 3700 Å. The speed of the star relative to the earth is [Speed of light \[3\times {{10}^{8}}m/s\]] [MP PET 1997]
  A)
             \[3\times {{10}^{5}}m/s\]       done clear
  B)
             \[3\times {{10}^{6}}m/s\] done clear
  C)
             \[3.7\times {{10}^{7}}m/s\]   done clear
  D)
             \[3.7\times {{10}^{6}}m/s\] done clear
  View Solution play_arrow

• question_answer20)
  In the spectrum of light of a luminous heavenly body the wavelength of a spectral line is measured to be 4747 Å while actual wavelength of the line is 4700 Å. The relative velocity of the heavenly body with respect to earth will be (velocity of light is \[3\times {{10}^{8}}m/s\])                                                             [MP PMT/PET 1998]
  A)
             \[3\times {{10}^{5}}m/s\]moving towards the earth done clear
  B)
             \[3\times {{10}^{5}}m/s\]moving away from the earth done clear
  C)
             \[3\times {{10}^{6}}m/s\]moving towards the earth done clear
  D)
             \[3\times {{10}^{6}}m/s\]moving away from the earth done clear
  View Solution play_arrow

• question_answer21)
  The wavelength of light observed on the earth, from a moving star is found to decrease by 0.05%. Relative to the earth the star is                                                          [MP PMT/PET 1998]
  A)
             Moving away with a velocity of \[1.5\times {{10}^{5}}m/s\] done clear
  B)
             Coming closer with a velocity of \[1.5\times {{10}^{5}}m/s\] done clear
  C)
             Moving away with a velocity of \[1.5\times {{10}^{4}}m/s\] done clear
  D)
             Coming closer with a velocity of \[1.5\times {{10}^{4}}m/s\] done clear
  View Solution play_arrow

• question_answer22)
  A star is going away from the earth. An observer on the earth will see the wavelength of light coming from the star         [MP PMT 1999]
  A)
             Decreased done clear
  B)
             Increased done clear
  C)
             Neither decreased nor increased done clear
  D)
             Decreased or increased depending upon the velocity of the star done clear
  View Solution play_arrow

• question_answer23)
  A star is moving towards the earth with a speed of \[4.5\times {{10}^{6}}\]m/s. If the true wavelength of a certain line in the spectrum received from the star is\[5890\,\,{AA}\], its apparent wavelength will be about \[[c=3\times {{10}^{8}}m/s]\]                             [MP PMT 1999]
  A)
  \[5890\,\,{AA}\] done clear
  B)
  \[5978\,\,{AA}\] done clear
  C)
  \[5802\,\,{AA}\]                done clear
  D)
  \[5896\,\,{AA}\] done clear
  View Solution play_arrow

• question_answer24)
  Due to Doppler's effect, the shift in wavelength observed is 0.1 Å for a star producing wavelength 6000 Å. Velocity of recession of the star will be
  A)
             2.5 km/s                                  done clear
  B)
             10 km/s done clear
  C)
             5 km/s                                     done clear
  D)
             20 km/s done clear
  View Solution play_arrow

• question_answer25)
  A rocket is going away from the earth at a speed of 106 m/s If the wavelength of the light wave emitted by it be \[5700\,\,{AA}\], what will be its Doppler's shift                                               [RPMT 1996]
  A)
  \[200\,\,{AA}\] done clear
  B)
  \[19\,\,{AA}\] done clear
  C)
  \[20\,\,{AA}\] done clear
  D)
  \[0.2\,\,{AA}\] done clear
  View Solution play_arrow

• question_answer26)
  A rocket is going away from the earth at a speed 0.2c, where c = speed of light. It emits a signal of frequency \[4\times {{10}^{7}}Hz\]. What will be the frequency observed by an observer on the earth                                            [RPMT 1996]
  A)
             \[4\times {{10}^{6}}Hz\]  done clear
  B)
             \[3.2\times {{10}^{7}}Hz\] done clear
  C)
             \[3\times {{10}^{6}}Hz\]  done clear
  D)
             \[5\times {{10}^{7}}Hz\] done clear
  View Solution play_arrow

• question_answer27)
  If a star is moving towards the earth, then the lines are shifted towards                                                [AIIMS 1997]
  A)
             Red                                           done clear
  B)
             Infrared done clear
  C)
             Blue                                          done clear
  D)
             Green done clear
  View Solution play_arrow

• question_answer28)
  When the wavelength of light coming from a distant star is measured it is found shifted towards red. Then the conclusion is                                                                       [JIPMER 1999]
  A)
             The star is approaching the observer done clear
  B)
             The star recedes away from earth done clear
  C)
             There is gravitational effect on the light done clear
  D)
             The star remains stationary done clear
  View Solution play_arrow

• question_answer29)
  A heavenly body is receding from earth such that the fractional change in l is 1, then its velocity is           [DCE 2000]
  A)
             C     done clear
  B)
             \[\frac{3C}{5}\] done clear
  C)
             \[\frac{C}{5}\]                      done clear
  D)
             \[\frac{2C}{5}\] done clear
  View Solution play_arrow

• question_answer30)
  The\[6563\,\,{AA}\]line emitted by hydrogen atom in a star is found to be red shifted by\[5\,\,{AA}\]. The speed with which the star is receding from the earth is                                                          [Pb. PMT 2002]
  A)
  17.29 - 109 m/s                    done clear
  B)
  4.29 - 107 m/s  done clear
  C)
  3.39 - 105 m/s                       done clear
  D)
  2.29 - 105 m/s done clear
  View Solution play_arrow

• question_answer31)
  Three observers A, B and C measure the speed of light coming from a source to be \[{{v}_{A}}\], \[{{v}_{B}}\] and \[{{v}_{C}}\]. The observer A moves towards the source, the observer C moves away from the source with the same speed. The observer B stays stationary. The surrounding space is vacuum everywhere. Then                                      [KCET 2002]
  A)
             \[{{v}_{A}}>{{v}_{B}}>{{v}_{C}}\]                                     done clear
  B)
             \[{{v}_{A}}<{{v}_{B}}<{{v}_{C}}\] done clear
  C)
             \[{{v}_{A}}={{v}_{B}}={{v}_{C}}\]                                     done clear
  D)
             \[{{v}_{A}}={{v}_{B}}>{{v}_{C}}\] done clear
  View Solution play_arrow

• question_answer32)
  Light from the constellation Virgo is observed to increase in wavelength by 0.4%. With respect to Earth the constellation is                                                                                            [MP PET 2003]
  A)
             Moving away with velocity 1.2 ´ 106 m/s done clear
  B)
             Coming closer with velocity 1.2 ´ 106 m/s  done clear
  C)
             Moving away with velocity 4 ´ 106 m/s done clear
  D)
             Coming closer with velocity 4 ´ 106 m/s done clear
  View Solution play_arrow

• question_answer33)
  It is believed that the universe is expanding and hence the distant stars are receding from us. Light from such a star will show                                                           [CPMT 2005]
  A)
             Shift in frequency towards longer wavelengths done clear
  B)
             Shift in frequency towards shorter wavelength done clear
  C)
             No shift in frequency but a decrease in intensity done clear
  D)
             A shift in frequency sometimes towards longer and sometimes towards shorter wavelengths done clear
  View Solution play_arrow