JEE Main & Advanced Physics Photo Electric Effect, X- Rays & Matter Waves Question Bank

done Cathode Rays and Positive Rays Total Questions - 72

• question_answer1)
  In the Millikan's experiment, the distance between two horizontal plates is 2.5 cm and the potential difference applied is 250 V. The electric field between the plates will be
  A)
             900 V/m                                  done clear
  B)
             10000 V/m done clear
  C)
             625 V/m                                  done clear
  D)
             6250 V/m done clear
  View Solution play_arrow

• question_answer2)
  The cathode rays have particle nature because of the fact that                                   [CPMT 1986; MNR 1986]
  A)
             They can propagate in vacuum done clear
  B)
             They are deflected by electric and magnetic fields done clear
  C)
             They produced fluorescence done clear
  D)
             They cast shadows done clear
  View Solution play_arrow

• question_answer3)
  In Millikan's experiment for the determination of the charge on the electron, the reason for using the oil is
  A)
             It is a lubricant                      done clear
  B)
             Its density is higher done clear
  C)
             It vapourises easily             done clear
  D)
             It does not vapourise done clear
  View Solution play_arrow

• question_answer4)
  The mass of a particle is 400 times than that of an electron and the charge is double. The particle is accelerated by 5 V. Initially the particle remained in rest, then its final kinetic energy will be                                [MP PMT 1990]
  A)
             5 eV                                          done clear
  B)
             10 eV done clear
  C)
             100 eV                                      done clear
  D)
             2000 eV done clear
  View Solution play_arrow

• question_answer5)
  An electron (charge =\[1.6\times {{10}^{-19}}C\]) is accelerated through a potential of 100,000 V. The energy acquired by the electron is                                                        [MP PET 1989]
  A)
             \[1.6\times {{10}^{-24}}\ J\]   done clear
  B)
             \[1.6\times {{10}^{-14}}\ erg\] done clear
  C)
             \[0.53\times {{10}^{-17}}J\]   done clear
  D)
             \[1.6\times {{10}^{-14}}J\] done clear
  View Solution play_arrow

• question_answer6)
  While doing his experiment, Millikan one day observed the following charges on a single drop            (i)   \[6.563\times {{10}^{-19}}C\] (ii)  \[8.204\times {{10}^{-19}}C\]            (iii)  \[11.50\times {{10}^{-19}}C\] (iv)  \[13.13\times {{10}^{-19}}C\]            (v)  \[16.48\times {{10}^{-19}}C\] (vi)  \[18.09\times {{10}^{-19}}C\]    From this data the value of the elementary charge (e) was found to be                                        [MP PMT 1993]
  A)
             \[1.641\times {{10}^{-19}}C\]                                            done clear
  B)
             \[1.630\times {{10}^{-19}}C\] done clear
  C)
             \[1.648\times {{10}^{-19}}C\]                                            done clear
  D)
             \[1.602\times {{10}^{-19}}C\] done clear
  View Solution play_arrow

• question_answer7)
  When electron beam passes through an electric field, they gain kinetic energy. If the same beam passes through magnetic field, then
  A)
             Their energy increases done clear
  B)
             Their momentum increases done clear
  C)
             Their potential energy increases done clear
  D)
             Energy and momentum both remains unchanged done clear
  View Solution play_arrow

• question_answer8)
  Which of the following law is used in the Millikan's method for the determination of charge [DPMT 2002]
  A)
             Ampere's law                       done clear
  B)
             Stoke's law done clear
  C)
             Fleming's left hand rule    done clear
  D)
             Fleming's right hand rule done clear
  View Solution play_arrow

• question_answer9)
  The mass of the electron varies with
  A)
             The size of the cathode ray tube done clear
  B)
             The variation of ?g? done clear
  C)
             Velocity done clear
  D)
             Size of the electron done clear
  View Solution play_arrow

• question_answer10)
  When the speed of electrons increases, then the value of its specific charge                                       [MP PMT 1994]
  A)
             Increases done clear
  B)
             Decreases done clear
  C)
             Remains unchanged done clear
  D)
             Increases upto some velocity and then begins to decrease done clear
  View Solution play_arrow

• question_answer11)
  An electron is accelerated through a potential difference of 1000 volts. Its velocity is nearly [MP PMT 1985; Pb. PET 2003]
  A)
             \[\frac{{{\nu }_{1}}-{{\nu }_{2}}}{k-1}\]                        done clear
  B)
             \[1.9\times {{10}^{6}}m/s\] done clear
  C)
             \[1.9\times {{10}^{7}}m/s\]   done clear
  D)
             \[2\sqrt{2}V\] done clear
  View Solution play_arrow

• question_answer12)
  In an electron gun the control grid is given a negative potential relative to cathode in order to    [NCERT 1988]
  A)
             Decelerate electrons done clear
  B)
             Repel electrons and thus to control the number of electrons passing through it done clear
  C)
             To select electrons of same velocity and to converge them along the axis done clear
  D)
             To decrease the kinetic energy of electrons done clear
  View Solution play_arrow

• question_answer13)
  The ratio of momenta of an electron and an \[\alpha -\]particle which are accelerated from rest by a potential difference of 100 V is                                  [MNR 1994; RPET 1997]
  A)
             1     done clear
  B)
             \[\sqrt{\frac{2{{m}_{e}}}{{{m}_{\alpha }}}}\] done clear
  C)
             \[\sqrt{\frac{{{m}_{e}}}{{{m}_{\alpha }}}}\]                done clear
  D)
             \[\sqrt{\frac{{{m}_{e}}}{2{{m}_{\alpha }}}}\] done clear
  View Solution play_arrow

• question_answer14)
  When subjected to a transverse electric field, cathode rays move                                            [MP PET 1994]
  A)
             Down the potential gradient done clear
  B)
             Up the potential gradient done clear
  C)
             Along a hyperbolic path done clear
  D)
             Along a circular path done clear
  View Solution play_arrow

• question_answer15)
  The fact that electric charges are integral multiples of the fundamental electronic charge was proved experimentally by                                                                                      [MP PET 1994]
  A)
             Planck                                      done clear
  B)
             J.J. Thomson done clear
  C)
             Einstein                                   done clear
  D)
             Millikan done clear
  View Solution play_arrow

• question_answer16)
  In Millikan oil drop experiment, a charged drop of mass \[1.8\times {{10}^{-14}}kg\]is stationary between its plates. The distance between its plates is 0.90 cm and potential difference is 2.0 kilo volts. The number of electrons on the drop is [MP PMT 1994, 2003; MP PET 1997]
  A)
             500 done clear
  B)
             50 done clear
  C)
             5     done clear
  D)
             0 done clear
  View Solution play_arrow

• question_answer17)
  The charge on electron was discovered by  [BHU 1995; RPMT 1999; DCE 2004]
  A)
             J.J. Thomson                         done clear
  B)
             Neil Bohr done clear
  C)
             Millikan                                   done clear
  D)
             Chadwick done clear
  View Solution play_arrow

• question_answer18)
  From the following, what charges can be present on oil drops in Millikan's experiment                   [MP PET 1995]
  A)
             Zero, equal to the magnitude of charge on \[\alpha -\]particle done clear
  B)
             \[2e,\ 1.6\times {{10}^{-18}}C,\]                                      done clear
  C)
             \[1.6\times {{10}^{-19}}C,\ 2.5e\] done clear
  D)
             \[1.5e,\ e\] (Here e is the electronic charge) done clear
  View Solution play_arrow

• question_answer19)
  A narrow electron beam passes undeviated through an electric field \[E=3\times {{10}^{4}}volt/m\]and an overlapping magnetic field \[B=2\times {{10}^{-3}}Weber/{{m}^{2}}\]. If electric field and magnetic field are mutually perpendicular. The speed of the electrons is                                                       [MP PET 1995]
  A)
             60 m/s                                     done clear
  B)
             \[10.3\times {{10}^{7}}m/s\] done clear
  C)
             \[1.5\times {{10}^{7}}m/s\]   done clear
  D)
             \[0.67\times {{10}^{-7}}m/s\] done clear
  View Solution play_arrow

• question_answer20)
  In Thomson's method of determining e/m of electrons [MP PMT 1997
  A)
             Electric and magnetic fields are parallel to electrons beam done clear
  B)
             Electric and magnetic fields are perpendicular to each other and perpendicular to electrons beam done clear
  C)
             Magnetic field is parallel to the electrons beam done clear
  D)
             Electric field is parallel to the electrons beam done clear
  View Solution play_arrow

• question_answer21)
  Cathode rays enter into a uniform magnetic field perpendicular to the direction of the field. In the magnetic field their path will be                                                           [MP PMT/PET 1998]
  A)
             Straight line                           done clear
  B)
             Circle done clear
  C)
             Parabolic                                 done clear
  D)
             Ellipse done clear
  View Solution play_arrow

• question_answer22)
  The specific charge of an electron is [MP PMT/PET 1998; J&K CET 2004; Pb. PET 2002; MH CET 1999]
  A)
             \[1.6\times {{10}^{-19}}coulomb\] done clear
  B)
             \[4.8\times {{10}^{-10}}stat\ coulomb\] done clear
  C)
             \[1.76\times {{10}^{11}}coulomb/kg\] done clear
  D)
             \[|8|\times {{10}^{-15}}Hz\] done clear
  View Solution play_arrow

• question_answer23)
  An electron is moving with constant velocity along \[x-\]axis. If a uniform electric field is applied along \[y-\]axis, then its path in the \[x-y\] plane will be                    [MP PMT 1999]
  A)
             A straight line                       done clear
  B)
             A circle done clear
  C)
             A parabola                             done clear
  D)
             An ellipse done clear
  View Solution play_arrow

• question_answer24)
  Cathode rays are similar to visible light rays in that [SCRA 1994]
  A)
             They both can be deflected by electric and magnetic fields done clear
  B)
             They both have a definite magnitude of wavelength done clear
  C)
             They both can ionise a gas through which they pass done clear
  D)
             They both can expose a photographic plate done clear
  View Solution play_arrow

• question_answer25)
  Which one of the following devices makes use of the electrons to strike certain substances to produce fluorescence                   [SCRA 1994]
  A)
             Thermionic valve                 done clear
  B)
             Photoelectric cell done clear
  C)
             Cathode ray oscilloscope done clear
  D)
             Electron gun done clear
  View Solution play_arrow

• question_answer26)
  An oxide coated filament is useful in vacuum tubes because essentially                                 [SCRA 1994]
  A)
             It has high melting point done clear
  B)
             It can withstand high temperatures done clear
  C)
             It has good machanical strength done clear
  D)
             It can emit electrons at relatively lower temperatures done clear
  View Solution play_arrow

• question_answer27)
  Gases begin to conduct electricity at low pressure because [CBSE PMT 1994]
  A)
             At low pressure, gases turn to plasma done clear
  B)
             Colliding electrons can acquire higher kinetic energy due to increased mean free path leading to ionisation of atoms done clear
  C)
             Atoms break up into electrons and protons done clear
  D)
             The electrons in atoms can move freely at low pressure done clear
  View Solution play_arrow

• question_answer28)
  A beam of electrons is moving with constant velocity in a region having electric and magnetic fields of strength \[20\ V{{m}^{-1}}\]and 0.5 T at right angles to the direction of motion of the electrons. What is the velocity of the electrons [CBSE PMT 1996]
  A)
             20 \[m{{s}^{-1}}\]               done clear
  B)
             40 \[m{{s}^{-1}}\] done clear
  C)
             8 \[m{{s}^{-1}}\]                  done clear
  D)
             5.5 \[m{{s}^{-1}}\] done clear
  View Solution play_arrow

• question_answer29)
  Kinetic energy of emitted cathode rays is dependent on [CPMT 1996]
  A)
             Only voltage                          done clear
  B)
             Only work function done clear
  C)
             Both (a) and (b) done clear
  D)
             It does not depend upon any physical quantity done clear
  View Solution play_arrow

• question_answer30)
  The radius of the orbital of electron in the hydrogen atom 0.5 Å. The speed of the electron is \[2\times {{10}^{6}}m/s\]. Then the current in the loop due to the motion of the electron is [RPMT 1996]
  A)
             1 mA                                         done clear
  B)
             1.5 mA done clear
  C)
             2.5 mA                                     done clear
  D)
             \[1.5\times {{10}^{-2}}mA\] done clear
  View Solution play_arrow

• question_answer31)
  The kinetic energy of an electron which is accelerated through a potential of 100 volts is [MP PET 1986; CBSE PMT 1997; AIIMS 1998]
  A)
             \[1.602\times {{10}^{-17}}J\] done clear
  B)
             418.6 calories done clear
  C)
             \[1.16\times {{10}^{4}}K\]      done clear
  D)
             \[6.626\times {{10}^{-34}}\]W- sec done clear
  View Solution play_arrow

• question_answer32)
  When a proton is accelerated with 1 volt potential difference, then its kinetic energy is [CPMT 1997; CBSE PMT 1999; RPET 2003]
  A)
             \[\frac{1}{1840}eV\]          done clear
  B)
             1840 eV done clear
  C)
             1 eV                                          done clear
  D)
             1840 c2 eV done clear
  View Solution play_arrow

• question_answer33)
  Energy of electrons can be increased by allowing them [JIPMER 1997]
  A)
             To fall through electric potential done clear
  B)
             To move in high magnetic field done clear
  C)
             To fall from great heights done clear
  D)
             To pass through lead blocks done clear
  View Solution play_arrow

• question_answer34)
  Cathode rays and canal rays produced in a certain discharge tube are deflected in the same direction if [SCRA 1998]
  A)
             A magnetic field is applied normally done clear
  B)
             An electric field is applied normally done clear
  C)
             An electric field is applied tangentially done clear
  D)
             A magnetic field is applied tangentially done clear
  View Solution play_arrow

• question_answer35)
  In a Millikan's oil drop experiment the charge on an oil drop is calculated to be \[6.35\times {{10}^{-19}}C\]. The number of excess electrons on the drop is                                                            [MNR 1998]
  A)
             3.9  done clear
  B)
             4 done clear
  C)
             4.2  done clear
  D)
             6 done clear
  View Solution play_arrow

• question_answer36)
  Cathode rays consist of                                   [DCE 1999]
  A)
             Photons                                  done clear
  B)
             Electrons done clear
  C)
             Protons                                   done clear
  D)
             \[\alpha \]-particles done clear
  View Solution play_arrow

• question_answer37)
  A metal plate gets heated, when cathode rays strike against, it due to            [CPMT 2000; Pb. PET 2000]
  A)
             Kinetic energy of cathode rays done clear
  B)
             Potential energy of cathode rays done clear
  C)
             Linear velocity of cathode rays done clear
  D)
             Angular velocity of cathode rays done clear
  View Solution play_arrow

• question_answer38)
  Cathode rays are                                                             [RPET 2000]
  A)
             Positive rays                          done clear
  B)
             Neutral rays done clear
  C)
             He rays                                    done clear
  D)
             Electron waves done clear
  View Solution play_arrow

• question_answer39)
  An electron of charge ?e? coulomb passes through a potential difference of \[V\] volts. Its energy in ?joules? will be [MP PET 2000]
  A)
             \[V/e\]                                    done clear
  B)
             eV done clear
  C)
             \[e/V\]                                    done clear
  D)
             V done clear
  View Solution play_arrow

• question_answer40)
  An electron is accelerated through a potential difference of 200 volts. If \[e/m\] for the electron be \[1.6\times {{10}^{11}}\] coulomb/kg, the velocity acquired by the electron will be [MP PET 2000]
  A)
             \[8\times {{10}^{6}}\,m/s\]    done clear
  B)
             \[8\times {{10}^{5}}\,m/s\] done clear
  C)
             \[5.9\times {{10}^{6}}\,m/s\]                                            done clear
  D)
             \[5.9\times {{10}^{5}}\,m/s\] done clear
  View Solution play_arrow

• question_answer41)
  Which is not true with respect to the cathode rays [Kerala PET 2001]
  A)
             A stream of electrons done clear
  B)
             Charged particles done clear
  C)
             Move with speed same as that of light done clear
  D)
             Can be deflected by magnetic fields done clear
  View Solution play_arrow

• question_answer42)
  In Milikan?s experiment, an oil drop having charge q gets stationary on applying a potential difference V in between two plates separated by a distance ?d?. The weight of the drop is                                              [MP PMT 2001]
  A)
             \[qVd\]                                   done clear
  B)
             \[q\frac{d}{V}\] done clear
  C)
             \[\frac{q}{Vd}\]                   done clear
  D)
             \[q\frac{V}{d}\] done clear
  View Solution play_arrow

• question_answer43)
  Electron volt is a unit of                                          [MP PMT 2001]
  A)
             Potential                                 done clear
  B)
             Charge done clear
  C)
             Power                                      done clear
  D)
             Energy done clear
  View Solution play_arrow

• question_answer44)
  In Thomson experiment of finding \[e/m\] for electrons, beam of electron is replaced by that of muons (particle with same charge as of electrons but mass 208 times that of electrons). No deflection condition in this case satisfied if [Orissa (Engg.) 2002]
  A)
             B is increased 208 times done clear
  B)
             E is increased 208 times done clear
  C)
             B is increased 14.4 times done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer45)
  The colour of the positive column in a gas discharge tube depends on                                    [Kerala (Engg.) 2002]
  A)
             The type of glass used to construct the tube done clear
  B)
             The gas in the tube done clear
  C)
             The applied voltage done clear
  D)
             The material of the cathode done clear
  View Solution play_arrow

• question_answer46)
  Cathode rays are produced when the pressure is of the order of                              [Kerala (Engg.) 2002]
  A)
             2 cm of Hg                              done clear
  B)
             0.1 cm of Hg done clear
  C)
             0.01 mm of Hg                      done clear
  D)
             1 \[\mu m\] of Hg done clear
  View Solution play_arrow

• question_answer47)
  The speed of an electron having a wavelength of \[{{10}^{-10}}\,m\] is [AIIMS 2002]
  A)
             \[7.25\times {{10}^{6}}\,m/s\]                                          done clear
  B)
             \[6.26\times {{10}^{6}}\,m/s\] done clear
  C)
             \[5.25\times {{10}^{6}}\,m/s\]                                          done clear
  D)
             \[4.24\times {{10}^{6}}\,m/s\] done clear
  View Solution play_arrow

• question_answer48)
  Which of the following is not the property of a cathode ray [CBSE PMT 2002]
  A)
             It casts shadow                    done clear
  B)
             It produces heating effect done clear
  C)
             It produces flurosence done clear
  D)
             It does not deflect in electric field done clear
  View Solution play_arrow

• question_answer49)
  In a Thomson set-up for the determination of e/m, electrons accelerated by 2.5 \[kV\] enter the region of crossed electric and magnetic fields of strengths \[3.6\times {{10}^{4}}V{{m}^{-1}}\] and \[1.2\times {{10}^{-3}}T\] respectively and go through undeflected. The measured value of \[e/m\] of the electron is equal to                 [AMU 2002]
  A)
             \[1.0\times {{10}^{11}}C\text{-}k{{g}^{-1}}\]              done clear
  B)
             \[1.76\times {{10}^{11}}C\text{-}k{{g}^{-1}}\] done clear
  C)
             \[1.80\times {{10}^{11}}C\text{-}k{{g}^{-1}}\]           done clear
  D)
             \[1.85\times {{10}^{11}}C\text{-}k{{g}^{-1}}\] done clear
  View Solution play_arrow

• question_answer50)
  The ratio of specific charge of an \[\alpha \]-particle to that of a proton is                                             [BCECE 2003]
  A)
             2 : 1                                           done clear
  B)
             1 : 1 done clear
  C)
             1 : 2                                           done clear
  D)
             1 : 3 done clear
  View Solution play_arrow

• question_answer51)
  In Bainbridge mass spectrograph a potential difference of 1000 V is applied between two plates distant 1 cm apart and magnetic field in B = 1T. The velocity of undeflected positive ions in m/s from the velocity selector is  [RPMT 1998]
  A)
             \[{{10}^{7}}m/s\]                done clear
  B)
             \[{{10}^{4}}m/s\]                done clear
  C)
             \[{{10}^{5}}m/s\]                done clear
  D)
             \[{{10}^{2}}m/s\] done clear
  View Solution play_arrow

• question_answer52)
  When cathode rays (tube voltage ~ 10 kV) collide with the anode of high atomic weight then we get [MP PET 1985]
  A)
             Positive rays                          done clear
  B)
             X-rays done clear
  C)
             Gamma rays                          done clear
  D)
             Canal rays done clear
  View Solution play_arrow

• question_answer53)
  In Thomson's experiment if the value of q/m is the same for all positive ions striking the photographic plate, then the trace would be                                                               [RPMT 1986]
  A)
             Straight line                           done clear
  B)
             Parabolic done clear
  C)
             Circular                                    done clear
  D)
             Elliptical done clear
  View Solution play_arrow

• question_answer54)
  In a discharge tube at 0.02 mm, there is a formation of [CBSE PMT 1996]
  A)
             FDS                                           done clear
  B)
             CDS done clear
  C)
             Both space                             done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer55)
  Electric field and magnetic field in Thomson mass spectrograph are applied                                          [RPMT 1998]
  A)
             Simultaneously, perpendicular done clear
  B)
             Perpendicular but not simultaneously done clear
  C)
             Parallel but not simultaneously done clear
  D)
             Parallel simultaneously done clear
  View Solution play_arrow

• question_answer56)
  The current conduction in a discharged tube is due to  [CBSE PMT 1999]
  A)
             Electrons only                       done clear
  B)
             +ve ions and electrons      done clear
  C)
             ? ve ions and electrons     done clear
  D)
             + ve ions, ? ve ions and electrons done clear
  View Solution play_arrow

• question_answer57)
  In Milikan's oil drop experiment, a charged drop falls with terminal velocity V. If an electric field E is applied in vertically upward direction then it starts moving in upward direction with terminal velocity 2V. If magnitude of electric field is decreased to \[\frac{E}{2}\], then terminal velocity will become                [CBSE PMT 1999]
  A)
             \[\frac{V}{2}\]                      done clear
  B)
             V done clear
  C)
             \[\frac{3V}{2}\]                    done clear
  D)
             2V done clear
  View Solution play_arrow

• question_answer58)
  An electron is accelerated through a p.d. of 45.5 volt. The velocity acquired by it is (in ms-1)                          [AIIMS 2004]
  A)
             \[4\times {{10}^{6}}\]       done clear
  B)
             \[4\times {{10}^{4}}\] done clear
  C)
             \[{{10}^{6}}\]                        done clear
  D)
             Zero done clear
  View Solution play_arrow

• question_answer59)
  A cathode emits \[1.8\times {{10}^{14}}\] electrons per second, when heated. When 400V is applied to anode all the emitted electrons reach the anode. The charge on electron is \[1.6\times {{10}^{-19}}C\]. The maximum anode current is                [MP PMT 2004]
  A)
             \[2.7\mu A\]                         done clear
  B)
             \[29\mu A\] done clear
  C)
             \[72\mu A\]                          done clear
  D)
             29 mA done clear
  View Solution play_arrow

• question_answer60)
  Order of  q/m  ratio of proton, \[\alpha \]-particle and electron is             [AFMC 2004]
  A)
             \[e>p>\alpha \]                   done clear
  B)
             \[p>\alpha >e\] done clear
  C)
             \[e>\alpha >p\]                   done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer61)
  A charge of magnitude \[3e\] and mass \[2m\] is moving in an electric field \[\overrightarrow{E}.\] The acceleration imparted to the charge is             [DCE 2004]
  A)
             \[2Ee/3m\]                            done clear
  B)
             \[3Ee/2m\] done clear
  C)
             \[2m/3Ee\]                            done clear
  D)
             \[3m/2Ee\] done clear
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• question_answer62)
  An electron initially at rest, is accelerated through a potential difference of 200 volt, so that it acquires a velocity \[8.4\times {{10}^{6}}m/s.\] The value of e/m of electron will be                [DPMT 2003]
  A)
             \[2.76\times {{10}^{12}}C/kg\]                                         done clear
  B)
             \[1.76\times {{10}^{11}}C/kg\]                                         done clear
  C)
             \[0.76\times {{10}^{12}}C/kg\]                                         done clear
  D)
             None of these done clear
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• question_answer63)
  An a particle is accelerated through a p.d of \[{{10}^{6}}\] volt then K.E. of particle will be                                            [Pb. PET 2003]
  A)
             8 MeV                                      done clear
  B)
             4 MeV done clear
  C)
             2 MeV                                      done clear
  D)
             1 MeV done clear
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• question_answer64)
  Positive rays consists of                                    [RPMT 1996, 2003]
  A)
             Electrons                                done clear
  B)
             Neutrons done clear
  C)
             Positive ions                          done clear
  D)
             Electromagnetic waves done clear
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• question_answer65)
  \[{{O}^{++}},\ {{C}^{+}},\ H{{e}^{++}}\] and \[{{H}^{+}}\] ions are projected on the photographic plate with same velocity in a mass spectrograph. Which one will strike farthest    [RPMT 2003]
  A)
             \[{{O}^{++}}\]                      done clear
  B)
             \[{{C}^{+}}\] done clear
  C)
             \[H{{e}^{++}}\]                    done clear
  D)
             \[H_{2}^{+}\] done clear
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• question_answer66)
  An electron beam is moving between two parallel plates having electric field \[1.125\times {{10}^{-6}}N/m\]. A magnetic field \[3\times {{10}^{-10}}T\] is also applied so that beam of electrons do not deflect. The velocity of the electron is                                         [MH CHT 2004]
  A)
             \[4225\ m/s\]                       done clear
  B)
             \[3750\ m/s\] done clear
  C)
             \[2750\ m/s\]                       done clear
  D)
             \[3200\ m/s\] done clear
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• question_answer67)
  Positive rays was discovered by                             [RPMT 1998]
  A)
             Thomson                                done clear
  B)
             Goldstem done clear
  C)
             W. Crookes                            done clear
  D)
             Rutherford done clear
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• question_answer68)
  An electron is moving in electric field and magnetic field it will gain energy from                                                 [DCE 1998]
  A)
             Electric field                           done clear
  B)
             Magnetic field done clear
  C)
             Both of these                       done clear
  D)
             None of these done clear
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• question_answer69)
  If an electron oscillates at a frequency of 1 GHz it gives   [DCE 1999]
  A)
             X-rays                                      done clear
  B)
             Mirowaves done clear
  C)
             Infrared rays                         done clear
  D)
             None of these done clear
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• question_answer70)
  In an electron gun, the electrons are accelerated by the potential V.  If e is the charge and m is the mass of an electron, then the maximum velocity of these electrons will be                    [MP PMT 1987, 96; BHU 1995; MNR 1998]
  A)
             \[\frac{2eV}{m}\]               done clear
  B)
             \[\sqrt{\frac{2eV}{m}}\] done clear
  C)
             \[\sqrt{\frac{2m}{eV}}\]  done clear
  D)
             \[\frac{{{V}^{2}}}{2em}\] done clear
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• question_answer71)
  Which of the following have highest specific charge [BHU 2005]
  A)
             Positron                                  done clear
  B)
             Proton done clear
  C)
             He  done clear
  D)
             None of these done clear
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• question_answer72)
  In Millikan?s oil drop experiment, an oil drop of mass \[16\times {{10}^{-6}}kg\] is balanced by an electric field of \[{{10}^{6}}V/m.\] The charge in coulomb on the drop, assuming \[g=10\,m/{{s}^{2}}\] is                                             [UP SEAT 2005]
  A)
             \[6.2\times {{10}^{-11}}\]       done clear
  B)
             \[16\times {{10}^{-9}}\]           done clear
  C)
             \[16\times {{10}^{-11}}\]         done clear
  D)
             \[16\times {{10}^{-13}}\] done clear
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