181 + Interview Questions in ELECTRON IN GENERAL AWARENESS Page 2 InterviewSolution

51.	An electron is moving through a field. It is moving `(i)` opposite an electric field `(ii)` perpendicular to a magnetic field as shown. For each situation the de - Broglie wave length of electron A. Increasing, increasingB. Increasing, decreasingC. Decreasing, sameD. Same, Same
Answer» Correct Answer - C

Discussion

52.	An electron is moving in electron field and magnetic field it will gain energy fromA. Electric fieldB. Magnetic fieldC. Both of theseD. None of these
Answer» Correct Answer - A

Discussion

53.	If an electron oscillates at a frequency of 1 GHz it givesA. X-raysB. MirowavesC. Infrared raysD. None of these
Answer» Correct Answer - D

Discussion

54.	Assertion : In photoemissive cell inert gas is used. Reason : Inert gas in the photoemissive cell gives greater current.A. If both assertion and reason are true and the reason is the correct explanation of the assert ion.B. If both assertion and reason are true but reason is not the correct explanation of the assertion.C. If assertion is true but reason is false.D. If the assertion and reason both are false
Answer» Correct Answer - A

Discussion

55.	In a photoemissive cell, with exciting wavelength `lambda`, the faster electron has speed v. If the exciting wavelength is changed to `3lambda//4`, the speed of the fastest electron will beA. `v(3//4)^(1//2)`B. `v(4//3)^(1//2)`C. Less than `v(4//3)^(1//2)`D. Greater than `v(4//3)^(1//2)`
Answer» Correct Answer - D

Discussion

56.	For harder X-rays,A. The wavelength is higherB. The intensity is higherC. The frequency is higherD. The photon energy is lower
Answer» Correct Answer - C

Discussion

57.	Which of the following is accompanied by the characteristic `X` - ray emission ?A. `alpha-` particle emissionB. Electron emissionC. Positron emissionD. K-electron capture
Answer» Correct Answer - D

Discussion

58.	Assertion : Intensity of `X` - rays can be controlled by adjusting the filament current and voltage. Reason : The intensity of `X` - ray does not depends on number of `X`-ray photons emitted per second from the target.A. If both assertion and reason are true and the reason is the correct explanation of the assert ion.B. If both assertion and reason are true but reason is not the correct explanation of the assertion.C. If assertion is true but reason is false.D. If the assertion and reason both are false
Answer» Correct Answer - C

Discussion

59.	In a dark room of photography, generally red light is used. The reason isA. Most of the photographic films are not sensitive to red lightB. The frequency for red light is low and hence the energy hvof photons is lessC. (a) and (b) bothD. None of the above
Answer» Correct Answer - C

Discussion

60.	X - rays which can penetrate through longer distances in substance are calledA. Soft X-raysB. Continuous X-raysC. Hard X-raysD. None of the above
Answer» Correct Answer - C

Discussion

61.	The wavelength of X-rays is of the order ofA. CentimetreB. Micron (10 m)C. Angstrom (10-10 mD. Metre
Answer» Correct Answer - C

Discussion

62.	The shorted wavelength of X- rays emitted from an X- rays tube depends onA. Current in the tubeB. Voltage applied to the tubeC. Nature of gas in the tubeD. Atomic number of target material
Answer» Correct Answer - B

Discussion

63.	In a discharge tube at 0.02 mm, there is a formation ofA. FDSB. CDSC. Both spaceD. None of these
Answer» Correct Answer - B

Discussion

64.	Assertion: Isotopes of an element can be separated by using a mass spectrometer. Reason: Separation of isotopes is possible because of difference in electron numbers of isotope.A. If both assertion and reason are true and the reason is the correct explanation of the assert ion.B. If both assertion and reason are true but reason is not the correct explanation of the assertion.C. If assertion is true but reason is false.D. If assertion is false but reason is true.
Answer» Correct Answer - D

Discussion

65.	Characteristic X-rays are produced due toA. Break up of moleculesB. Changing in atomic energy levelC. Changing in nuclear energy levelD. Radioactive disintegration
Answer» Correct Answer - B

Discussion

66.	In a photoemissive cell, with exciting wavelength `lambda`, the faster electron has speed v. If the exciting wavelength is changed to `3lambda//4`, the speed of the fastest electron will beA. `v(3//4)^(1//2)`B. `v(4//3)^(1//2)`C. Less than `v(4//3)6(1//2)`D. Greater than `v(4//3)^(1//2)`
Answer» Correct Answer - D

Discussion

67.	An electron beam is moving between two parallel plates having eletric field `1.125 xx 10^(-6) N//m`. A magnetic field `3 xx 10^(-10) T` is also applied so that beam of electrons do not deflect. The velocity of the electron isA. 4225 m/sB. 3750 m/sC. 2750 m/sD. 3200 m/s
Answer» Correct Answer - B

Discussion

68.	In Bainbridge mass spectograph a potential difference of 1000 V is applied between two plates distant 1 cm apart and magnetic field in `B = 1T`. The velocity of unflected positive ions in m//s from the velocity selector isA. `10^(7) m//s`B. `10^(4) m//s`C. `10^(5) m//s`D. `10^(2) m//s`
Answer» Correct Answer - C

Discussion

69.	The spectrum of radiation `1.0 xx 10^(14) Hz` is the infrared region. The energy of one photon of this in joules will beA. `6.62 xx 10^(-48)`B. `6.62 xx 10^(-20)`C. `(6.62)/(3)xx10^(-28)`D. `3 xx 6.62 xx 10^(-28)`
Answer» Correct Answer - B

Discussion

70.	If light of wavelength `lambda_(1)` is allowed to fall on a metal , then kinetic energy of photoelectrons emitted is `E_(1)`. If wavelength of light changes to `lambda_(2)` then kinetic energy of electrons changes to `E_(2)`. Then work function of the metal isA. `(E_(1)E_(2)(lambda_(1)-lambda_(2)))/(lambda_(1)lambda_(2))`B. `(E_(1)lambda_(1)-E_(2)lambda_(2))/(lambda_(1)-lambda_(2))`C. `(E_(1)lambda_(1)-E_(2)lambda_(2))/(lambda_(2)-lambda_(1))`D. `(lambda_(1)lambda_(2)E_(1)E_(2))/(lambda_(2)-lambda_(1))`
Answer» Correct Answer - C

Discussion

71.	An image of the sun is formed by a lens, of the focal length of 30 cm, on the metal surface of a photoelectric cell and a photoelectric current I is produced. The lens forming the image is then replaced by another of the same diameter but of focal length 15 cm. The photoelectric current in this case isA. `(I)/(2)`B. `I`C. `2I`D. `4I`
Answer» Correct Answer - D

Discussion

72.	An electron is accelerated through a potential difference of 1000 volts .Its velocity is nearlyA. `3.8 xx 10^(7) m//s`B. `1.9 xx10^(6) m//s`C. `1.9 xx 10^(7) m//s`D. `5.7 xx 10^(7) m//s`
Answer» Correct Answer - C

Discussion

73.	For continuous X-rays produced wavelength isA. Inversely proportional to the energy of the electrons hitting the targetB. Inversely proportional to the intensity of the electron beamC. Proportional to intensity of the electron beamD. Proportional to target temperature
Answer» Correct Answer - A

Discussion

74.	If the threshold wavelength for sodium is `5420 Å`, then the work function of sodium isA. 4.58 eVB. 2.38 eVC. 1.14 eVD. 0.23 eV
Answer» Correct Answer - B

Discussion

75.	Photo cell is a device toA. Store photonsB. Measure light intensityC. Convert photon energy into mechanical energyD. Store electrical energy for replacing storage batteries
Answer» Correct Answer - B

Discussion

76.	Threshold frequency for a metal is `10^(15) Hz`. Light of `lambda = 4000 Å` falls on its surface . Which of the following statements is correct ?A. No photoelectric emission takes placeB. Photo-electrons come out with zero speedC. Photo-electrons come out with 103 m/sec speedD. Photo-electrons come out with 105 m/sec speed
Answer» Correct Answer - A

Discussion

77.	If the threshold wavelength for sodium is `5420 Å`, then the work function of sodium isA. 4.58 eVB. 2.29 eVC. 1.14 eVD. 0.57 eV
Answer» Correct Answer - B

Discussion

78.	The wavelength of the most energetic X–ray emitted when a metal target is bombarded by 100 KeV electrons is approximatelyA. 12 ÅB. 4C. 0.31 ÅD. 0.124 Å
Answer» Correct Answer - D

Discussion

79.	Electrons with energy `80 keV` are incident on the tungsten target of an X - rays tube , k- shell electrons of tungsten have `72.5 keV` energy X- rays emitted by the tube contain onlyA. A continuous X - ray spectrum (Bremsstrahlung) with a minimum wavelength of `~ 0.155Å`B. A continuous X - ray spectrum (Bremsstrahlung] with all wavelengthsC. The characteristic X - rays spectrum of tungstenD. A continuous X - ray spectrum (Bremsstrahlung) with a minimum wavelength of `~ 0.155Å` and the characteristic X - ray spectrum of tungsten
Answer» Correct Answer - D

Discussion

80.	If the de - Broglie wavelengths for a proton and for a `alpha` - particle are equal , then the ratio of their velocities will beA. `4:1`B. `2:1`C. `1:2`D. `1:4`
Answer» Correct Answer - A

Discussion

81.	In a Thomson set-up for the demination of e/m, electrons accelerated by 2.5 kV enter the region of crossed electric and magnetic fields of strengths `3.6 xx 10^(4) Vm^(-1) and 1.2 xx 10^(-3) T` respectively and through undeflected. The meaured value of `e//m` of the electron is equal toA. `1.0 xx 10^(11) C-kg^(-1)`B. `1.76 xx 10^(11) C-kg^(-1)`C. `1.80 xx 10^(11) C-kg^(-1)`D. `1.85 xx 10^(11) C-kg^(-1)`
Answer» Correct Answer - C

Discussion

82.	The ratio of specific charge of an `alpha-` particle to that of a proton isA. `2:1`B. `1:1`C. `1:2`D. `1:3`
Answer» Correct Answer - C

Discussion

83.	The eye can detect `5xx10^(4)` photons `(m^2s)^(-1)` of green light (`lamda=5000A)`, whole ear can detect `10^(-13)Wm^(2)` . As a power detector, which is more sensitive and by what factor?A. 5B. 10C. `10^(6)`D. `15`
Answer» Correct Answer - A

Discussion

84.	The eye can detect `5xx10^(4)` photons `(m^2s)^(-1)` of green light (`lamda=5000A)`, whole ear can detect `10^(-13)Wm^(2)` . As a power detector, which is more sensitive and by what factor?A. 5B. 10C. 10D. 15
Answer» Correct Answer - A

Discussion

85.	An X - ray machine has an accelerating potential difference of 25,000 volts. By calculation the shortest wavelength will be obtained as `(h=6.62 xx10^(-34)J-sec,e=1.6xx10^(-19)"coulomb")`A. 0.25 ÅB. 0.50 ÅC. 1.00 ÅD. 2.50 Å
Answer» Correct Answer - B

Discussion

86.	Monochromatic light of wavelength `3000 Å` is incident on a surface area `4 cm^(2)`. If intensity of light is `150 m W//m^(2)` , then rate at which photons strike the target isA. `3 xx 10//sec`B. `9 xx 10//sec`C. `7xx 10//sec`D. `6 xx 10//sec`
Answer» Correct Answer - B

Discussion

87.	For characteristic `X` - ray of some materialA. `E(K_(gamma))ltE(K_(beta))lt E(K_(alpha))`B. `E(K_(alpha))ltE(L_(alpha))lt E(M_(alpha))`C. `lamda(K_(gamma))lt lamda(K_(beta))lt lamda(K_(alpha))`D. `lamda(M_(alpha))lt lamda(L_(alpha))lt lamda(K_(alpha))`
Answer» Correct Answer - C

Discussion

88.	A photon collides with a stationary hydrogen atom in ground state inelastically. Energy of the colliding photon is 10.2 eV. After a time interval of the order of micro second another photon collides with same hydrogen atom inelastically with an energy of 15eV. What wil be observed by the detector? (a) 2 photons of energy 10.2 eV (b) 2 photons of energy 1.4 eV (c ) One photon of energy 10.2 eV and an electron of energy 1.4 eV (d) One photon of energy 10.2 eV and another photon of energy 1.4 eVA. 2 photon of energy 10.2 eVB. 2 photon of energy of 1.4 eVC. One photon of energy 10.2 eV and an electron of energy 1.4 eVD. One photon of energy 10.2 eV and another photon of 1.4 eV
Answer» Correct Answer - C

Discussion

89.	An important spetral emission line has a wavelength of 21 cm. The corresponding photon energy is `(h=6.62 xx10^(-34)Js ,c=3xx10^(8)m//s)`A. `5.9 xx 10^(4) eV`B. `5.9 xx 10^(-6) eV`C. `5.9 xx 10^(-8) eV`D. `11.8 xx10^(-6) eV`
Answer» Correct Answer - B

Discussion

90.	Which of the following statement is not correctA. Photographic plates are sensitive to infrared raysB. Photographic plates are sensitive to ultraviolet raysC. Infra-red rays are invisible but can cast shadows like visible lightD. Infrared photons have more energy than photons of visible light
Answer» Correct Answer - D

Discussion

91.	If we express the energy of a photon in `KeV` and the wavelength in angstroms , then energy of a photon can be calculated from the relationA. `E = 12.4 hv`B. `E = 12.4 h//lamda`C. `E = 12.4//lamda`D. `E = hv`
Answer» Correct Answer - C

Discussion

92.	The frequency of a photon , having energy `100 eV is ( h = 6.610^(-34) J - sec)`A. `2.43 xx 10^(26) Hz`B. `2.42 xx 10^(16) Hz`C. `2.42 xx 10^(12) Hz`D. `2.42 xx 10^(9) Hz`
Answer» Correct Answer - B

Discussion

93.	The photo-electrons emitted from a surface of sodium metal are such thatA. They all are of the same frequencyB. They have the same kinetic energyC. They have the same de Broglie wavelengthD. They have their speeds varying from zero to a certain maximum
Answer» Correct Answer - D

Discussion

94.	Assertion : Mass of moving photon varies inversely as the wavelength . Reason : Energy of the particle `= Mass xx (Speed of light)^(2)`A. If both assertion and reason are true and the reason is the correct explanation of the assert ion.B. If both assertion and reason are true but reason is not the correct explanation of the assertion.C. If assertion is true but reason is false.D. If the assertion and reason both are false
Answer» Correct Answer - B

Discussion

95.	If a photon has velocity `c` and frequency `n` , then which of following represents its wavelength ?A. `(hc)/(E)`B. `(hv)/(c)`C. `(hv)/(c^(2))`D. `hv`
Answer» Correct Answer - A

Discussion

96.	The frequency of incident light falling on a photosensitive metal plate is doubled, the K.E of the emitted photo-electrons isA. Double the earlier valueB. UnchangedC. More than doubledD. Less than doubled
Answer» Correct Answer - C

Discussion

97.	Energy of photon whose frequency is `10^(12) MHz`, will beA. `4.14 xx 10^(3) keV`B. `4.14 xx 10^(2) eV`C. `4.14 xx 10^(3) MeV`D. `4.14 xx 10^(3) eV`
Answer» Correct Answer - D

Discussion

98.	Assertion : Kinetic energy of photo electrons emitted by a photosensitive surface depends upon the intensity of incident photon. Reason : The ejection of electrons from metallic surface is possible with frequency of incident photon below the threshold frequency.A. If both assertion and reason are true and the reason is the correct explanation of the assert ion.B. If both assertion and reason are true but reason is not the correct explanation of the assertion.C. If assertion is true but reason is false.D. If the assertion and reason both are false
Answer» Correct Answer - D

Discussion

99.	When green light is incident on the surface of metal , it emits photo - electrons but there is no such emission with yellow colour light. Which one of the colours can produce emission of photo - electrons ?A. OrangeB. RedC. IndigoD. None of the above
Answer» Correct Answer - C

Discussion

100.	If maximum velocity with which an electron can be emitted from a photo cell is `4 xx 10^(8) cm//sec` , the stopping potential is (mass of electron ` = 9 xx -31 kg`)A. 30 voltB. 45 voltC. 59 voltD. Information is insufficient
Answer» Correct Answer - B

Discussion

Explore topic-wise InterviewSolutions in .

An electron is moving through a field. It is moving `(i)` opposite an electric field `(ii)` perpendicular to a magnetic field as shown. For each situation the de - Broglie wave length of electron A. Increasing, increasingB. Increasing, decreasingC. Decreasing, sameD. Same, Same

An electron is moving in electron field and magnetic field it will gain energy fromA. Electric fieldB. Magnetic fieldC. Both of theseD. None of these

If an electron oscillates at a frequency of 1 GHz it givesA. X-raysB. MirowavesC. Infrared raysD. None of these

In a photoemissive cell, with exciting wavelength `lambda`, the faster electron has speed v. If the exciting wavelength is changed to `3lambda//4`, the speed of the fastest electron will beA. `v(3//4)^(1//2)`B. `v(4//3)^(1//2)`C. Less than `v(4//3)^(1//2)`D. Greater than `v(4//3)^(1//2)`

For harder X-rays,A. The wavelength is higherB. The intensity is higherC. The frequency is higherD. The photon energy is lower

Which of the following is accompanied by the characteristic `X` - ray emission ?A. `alpha-` particle emissionB. Electron emissionC. Positron emissionD. K-electron capture

In a dark room of photography, generally red light is used. The reason isA. Most of the photographic films are not sensitive to red lightB. The frequency for red light is low and hence the energy hvof photons is lessC. (a) and (b) bothD. None of the above

X - rays which can penetrate through longer distances in substance are calledA. Soft X-raysB. Continuous X-raysC. Hard X-raysD. None of the above

The wavelength of X-rays is of the order ofA. CentimetreB. Micron (10 m)C. Angstrom (10-10 mD. Metre

The shorted wavelength of X- rays emitted from an X- rays tube depends onA. Current in the tubeB. Voltage applied to the tubeC. Nature of gas in the tubeD. Atomic number of target material

In a discharge tube at 0.02 mm, there is a formation ofA. FDSB. CDSC. Both spaceD. None of these

Characteristic X-rays are produced due toA. Break up of moleculesB. Changing in atomic energy levelC. Changing in nuclear energy levelD. Radioactive disintegration

In a photoemissive cell, with exciting wavelength `lambda`, the faster electron has speed v. If the exciting wavelength is changed to `3lambda//4`, the speed of the fastest electron will beA. `v(3//4)^(1//2)`B. `v(4//3)^(1//2)`C. Less than `v(4//3)6(1//2)`D. Greater than `v(4//3)^(1//2)`

An electron beam is moving between two parallel plates having eletric field `1.125 xx 10^(-6) N//m`. A magnetic field `3 xx 10^(-10) T` is also applied so that beam of electrons do not deflect. The velocity of the electron isA. 4225 m/sB. 3750 m/sC. 2750 m/sD. 3200 m/s

In Bainbridge mass spectograph a potential difference of 1000 V is applied between two plates distant 1 cm apart and magnetic field in `B = 1T`. The velocity of unflected positive ions in m//s from the velocity selector isA. `10^(7) m//s`B. `10^(4) m//s`C. `10^(5) m//s`D. `10^(2) m//s`

The spectrum of radiation `1.0 xx 10^(14) Hz` is the infrared region. The energy of one photon of this in joules will beA. `6.62 xx 10^(-48)`B. `6.62 xx 10^(-20)`C. `(6.62)/(3)xx10^(-28)`D. `3 xx 6.62 xx 10^(-28)`

An electron is accelerated through a potential difference of 1000 volts .Its velocity is nearlyA. `3.8 xx 10^(7) m//s`B. `1.9 xx10^(6) m//s`C. `1.9 xx 10^(7) m//s`D. `5.7 xx 10^(7) m//s`

For continuous X-rays produced wavelength isA. Inversely proportional to the energy of the electrons hitting the targetB. Inversely proportional to the intensity of the electron beamC. Proportional to intensity of the electron beamD. Proportional to target temperature

If the threshold wavelength for sodium is `5420 Å`, then the work function of sodium isA. 4.58 eVB. 2.38 eVC. 1.14 eVD. 0.23 eV

Photo cell is a device toA. Store photonsB. Measure light intensityC. Convert photon energy into mechanical energyD. Store electrical energy for replacing storage batteries

If the threshold wavelength for sodium is `5420 Å`, then the work function of sodium isA. 4.58 eVB. 2.29 eVC. 1.14 eVD. 0.57 eV

The wavelength of the most energetic X–ray emitted when a metal target is bombarded by 100 KeV electrons is approximatelyA. 12 ÅB. 4C. 0.31 ÅD. 0.124 Å

If the de - Broglie wavelengths for a proton and for a `alpha` - particle are equal , then the ratio of their velocities will beA. `4:1`B. `2:1`C. `1:2`D. `1:4`

The ratio of specific charge of an `alpha-` particle to that of a proton isA. `2:1`B. `1:1`C. `1:2`D. `1:3`

The eye can detect `5xx10^(4)` photons `(m^2s)^(-1)` of green light (`lamda=5000A)`, whole ear can detect `10^(-13)Wm^(2)` . As a power detector, which is more sensitive and by what factor?A. 5B. 10C. `10^(6)`D. `15`

The eye can detect `5xx10^(4)` photons `(m^2s)^(-1)` of green light (`lamda=5000A)`, whole ear can detect `10^(-13)Wm^(2)` . As a power detector, which is more sensitive and by what factor?A. 5B. 10C. 10D. 15

An X - ray machine has an accelerating potential difference of 25,000 volts. By calculation the shortest wavelength will be obtained as `(h=6.62 xx10^(-34)J-sec,e=1.6xx10^(-19)"coulomb")`A. 0.25 ÅB. 0.50 ÅC. 1.00 ÅD. 2.50 Å

Monochromatic light of wavelength `3000 Å` is incident on a surface area `4 cm^(2)`. If intensity of light is `150 m W//m^(2)` , then rate at which photons strike the target isA. `3 xx 10//sec`B. `9 xx 10//sec`C. `7xx 10//sec`D. `6 xx 10//sec`

For characteristic `X` - ray of some materialA. `E(K_(gamma))ltE(K_(beta))lt E(K_(alpha))`B. `E(K_(alpha))ltE(L_(alpha))lt E(M_(alpha))`C. `lamda(K_(gamma))lt lamda(K_(beta))lt lamda(K_(alpha))`D. `lamda(M_(alpha))lt lamda(L_(alpha))lt lamda(K_(alpha))`

An important spetral emission line has a wavelength of 21 cm. The corresponding photon energy is `(h=6.62 xx10^(-34)Js ,c=3xx10^(8)m//s)`A. `5.9 xx 10^(4) eV`B. `5.9 xx 10^(-6) eV`C. `5.9 xx 10^(-8) eV`D. `11.8 xx10^(-6) eV`

Which of the following statement is not correctA. Photographic plates are sensitive to infrared raysB. Photographic plates are sensitive to ultraviolet raysC. Infra-red rays are invisible but can cast shadows like visible lightD. Infrared photons have more energy than photons of visible light

If we express the energy of a photon in `KeV` and the wavelength in angstroms , then energy of a photon can be calculated from the relationA. `E = 12.4 hv`B. `E = 12.4 h//lamda`C. `E = 12.4//lamda`D. `E = hv`

The frequency of a photon , having energy `100 eV is ( h = 6.610^(-34) J - sec)`A. `2.43 xx 10^(26) Hz`B. `2.42 xx 10^(16) Hz`C. `2.42 xx 10^(12) Hz`D. `2.42 xx 10^(9) Hz`

The photo-electrons emitted from a surface of sodium metal are such thatA. They all are of the same frequencyB. They have the same kinetic energyC. They have the same de Broglie wavelengthD. They have their speeds varying from zero to a certain maximum

If a photon has velocity `c` and frequency `n` , then which of following represents its wavelength ?A. `(hc)/(E)`B. `(hv)/(c)`C. `(hv)/(c^(2))`D. `hv`

The frequency of incident light falling on a photosensitive metal plate is doubled, the K.E of the emitted photo-electrons isA. Double the earlier valueB. UnchangedC. More than doubledD. Less than doubled

Energy of photon whose frequency is `10^(12) MHz`, will beA. `4.14 xx 10^(3) keV`B. `4.14 xx 10^(2) eV`C. `4.14 xx 10^(3) MeV`D. `4.14 xx 10^(3) eV`

When green light is incident on the surface of metal , it emits photo - electrons but there is no such emission with yellow colour light. Which one of the colours can produce emission of photo - electrons ?A. OrangeB. RedC. IndigoD. None of the above

If maximum velocity with which an electron can be emitted from a photo cell is `4 xx 10^(8) cm//sec` , the stopping potential is (mass of electron ` = 9 xx -31 kg`)A. 30 voltB. 45 voltC. 59 voltD. Information is insufficient