12

TH

STANDARD PHYSICS

ATOMIC PHYSICS

Prepared by: R.RAJENDRAN, M.A., M.Sc., M.Ed., N.INGARAN, M.Sc., M.Phil.,M.Ed.,

CHOOSE THE CORRECT ANSWER 1. At atmospheric pressure, air and other gases are …………… conductors of electricity. a) good b) semi c) poor d) rich

CHOOSE THE CORRECT ANSWER 2. Electric current may be passed through a gas by allowing ……………. to pass through them. a) light b) infra-red c) X –rays d) none of the above

CHOOSE THE CORRECT ANSWER 3. Electrons were discovered by ……………… a) Millikan b) Goldstein c) Einstein d) Thomson

CHOOSE THE CORRECT ANSWER 4. …………………… is an arrangement to study the conduction of electricity through gases. a) X-ray tube b) Coolidge tube c) discharge tube d) GM counter

CHOOSE THE CORRECT ANSWER 5. In a discharge tube, the potential difference applied between the two electrodes is ……………… a) 10000 V b) 20000 V c) 60000 V d) 50000 V

CHOOSE THE CORRECT ANSWER 6. In a discharge tube, the discharge of electricity through gases starts at a pressure of about …..

a) 100 mm of Hg b) 1 mm of Hg c) 10 mm of Hg d) 0.01 mm of Hg

CHOOSE THE CORRECT ANSWER 7. In a discharge tube, the positive column is produced at a pressure of about ……………… a) 100 mm of Hg b) 1 mm of Hg c) 10 mm of Hg d) 0.01 mm of Hg

CHOOSE THE CORRECT ANSWER 8. In a discharge tube, Crooke’s dark space is produced at a pressure of about …………… a) 100 mm of Hg b) 1 mm of Hg c) 10 mm of Hg d) 0.01 mm of Hg

CHOOSE THE CORRECT ANSWER 9. Cathode rays travel with a velocity up to ………………. of the velocity of light. a) (1 /100) th b) (1 /10) th c) (1 /1000) th d) (1 /10000) th

CHOOSE THE CORRECT ANSWER 10. Canal rays were discovered by ……………….in the year 1886. a) Millikan b) Goldstein c) Einstein d) Thomson

CHOOSE THE CORRECT ANSWER 11. In 1887, ………………… measured the specific charge of the cathode ray particles. a) Millikan b) Goldstein c) Einstein d) Thomson

CHOOSE THE CORRECT ANSWER 12. If V is the potential difference between the two plates and d is the distance between them, then E = … a) V d b) d / V c) V / d d) V 2 / d

CHOOSE THE CORRECT ANSWER 13. e / m value of the electron is …………………..

a) 1.7592 X 10 11 C kg -1 b) 1.7592 X 10 11 C kg c) 1.602 X 10 19 C kg -1 d) 1.602 X 10 -19 C kg -1

CHOOSE THE CORRECT ANSWER 14. Millikan’s experiment is used for the measurement of ………… of the electron. a) density b) specific charge c) mass d) charge

CHOOSE THE CORRECT ANSWER 15. In Millikan’s experiment, the potential difference applied between the two electrodes is ……… a) 10000 V b) 20000 V c) 60000 V d) 50000 V

CHOOSE THE CORRECT ANSWER 16. The net downward force acting on the oil drop = …………….. a) zero b) maximum c) minimum d) ⅓ X 4 π a3 ( ρ - ζ ) g

CHOOSE THE CORRECT ANSWER 17. In Millikan’s experiment, the charge of the electron q = …………… a) ⅓ X 4 π a3 ( ρ - ζ ) g b) 4 π a3 ( ρ - ζ ) g c) (⅓ )π a3 ( ρ - ζ ) g d) zero

CHOOSE THE CORRECT ANSWER 18. In Millikan’s experiment, the charge value of the electron = …………………. a) 1.7592 X 10 11 C kg -1 b) 1.7592 X 10 11 C kg c) 1.602 X 10 19 C kg -1 d) 1.602 X 10 -19 C kg -1

CHOOSE THE CORRECT ANSWER 19. The concept of atoms was proposed by …………… a) Bohr b) Thomson c) Dalton d) Prout

CHOOSE THE CORRECT ANSWER 20. Prout suggested that all elements are made up of atoms of ………………… a) carbon b) helium c) hydrogen d) nitrogen

CHOOSE THE CORRECT ANSWER 21. Atom is a sphere of positive charge in which the electrons are embedded. This was suggested by ..… a) Bohr b) Thomson c) Dalton d) Prout

CHOOSE THE CORRECT ANSWER 22. In the case of hydrogen atom, Thomson’s model gives only one spectral line of about …………… a) 3300 A o b) 2300 A o c) 1300 A o d) 4300 A o

CHOOSE THE CORRECT ANSWER 23. The scattering of α particles provide useful information about the structure of the ……………….. a) atom b) hydrogen c) CO 2 d) oxygen

CHOOSE THE CORRECT ANSWER 24. The diameter of the atom is about ………….. a) 10 -20 m b) 10 -10 m c) 10 -14 m d) 10 10 m

CHOOSE THE CORRECT ANSWER 25. The diameter of the nucleus is about ……………. a) 10 -20 m b) 10 -10 m c) 10 -14 m d) 10 10 m

CHOOSE THE CORRECT ANSWER 26. According to electromagnetic theory, an accelerated electric charge must radiate energy in the form of …… a) light b) infra-red rays c) X –rays d) electromagnetic waves

CHOOSE THE CORRECT ANSWER 27. An electron revolving in the stationary orbit does not radiate ………... a) lepton b) energy c) meson d) particle

CHOOSE THE CORRECT ANSWER 28. According to Bohr’s quantization condition, the angular momentum of the electron = …………… a) h / 2 b) 2 π / n h c) nh / 2π d) 2π nh

CHOOSE THE CORRECT ANSWER 29. The radius of the nth orbit of the electron is proportional to the square of the ……… quantum number a) spin b) principal c) magnetic d) angular momentum

CHOOSE THE CORRECT ANSWER 30. Bohr radius value r1 = ………………… a) 0.63 A o b) 0.83 A o c) 0.53 A o d) 0.43 A o

CHOOSE THE CORRECT ANSWER 31. The energy of the electron En = …………….. a) - z 2 me 4 / 8ε 0 2 n 2 h 2 b) z 2 me 4 / 8ε 0 2 n 2 h 2 c) n 2 h 2 ε 0 / π mze 2 d) - z 2 me 4 / 4ε 0 2 n 2 h 2

CHOOSE THE CORRECT ANSWER 32. 1 electron volt = ……………… J a) 1.602 X 10 19 b) 1.602 X 10 -19 c) 9.11 X 10 -31 d) 9.11 X 10 31

CHOOSE THE CORRECT ANSWER 33. Rydberg’s constant value R = ………………. a) 1.094 X 10 7 m -1 b) 1.602 X 10 9 c) 1.602 X 10 -19 d) 9.11 X 10 -31

CHOOSE THE CORRECT ANSWER 34. The spectral lines of Lyman series of hydrogen atom lie in the ………… region. a) UV b) Visible c) infra - red d) gamma

CHOOSE THE CORRECT ANSWER 35. The spectral lines of Balmer series of hydrogen atom lie in the …………….. a) UV b) Visible c) infra - red d) gamma

CHOOSE THE CORRECT ANSWER 36. The spectral lines of Paschen series of hydrogen atom lie in the ………………. a) UV b) Visible c) infra - red d) gamma

CHOOSE THE CORRECT ANSWER 37. The spectral lines of Brakett series of hydrogen atom lie in the ……………… a) UV b) Visible c) infra - red d) gamma

CHOOSE THE CORRECT ANSWER 38. The spectral lines of Pfund series of hydrogen atom lie in the ………….. a) UV b) Visible c) infra - red d) gamma

CHOOSE THE CORRECT ANSWER 39. The wavelengths of D1 and D2 lines of sodium are ................. a) 5809A o ,5896 A o b) 5986A o ,5980 A o c) 5689A o ,5690 A o d) 5896A o ,5890 A o

CHOOSE THE CORRECT ANSWER 40. The energy required to raise an atom from its normal state into an excited state is called ……. energy. a) excitation potential b) potential c) kinetic d) stellar

CHOOSE THE CORRECT ANSWER 41. The value of ionization potential energy for hydrogen atom is ………… a) 13.6 eV b) 30.6 eV c) 3.4 eV d) 10.2 eV

CHOOSE THE CORRECT ANSWER 42. The fine structure of spectral lines can not be explained by ………… theory. a) Raman b) Newton c) Bohr d) Huygens

CHOOSE THE CORRECT ANSWER 43. It is found that when magnetic field is applied to the atom, each of the spectral line is split into several lines. This effect is called ……… effect. a) Stark b) Zeeman c) Raman d) Tyndal

CHOOSE THE CORRECT ANSWER 44. According to Somerfield's atom model, for any principal quantum number n, there are n possible

sub-shells, out of which one is circular and the remaining two are ……………. in shape. a) elliptical c) semi-circular c) square d) rectangle

CHOOSE THE CORRECT ANSWER

45. X-rays were discovered by …………… a) Raman b) Newton c) Roentgen d) Huygens

CHOOSE THE CORRECT ANSWER

46. X-rays are electromagnetic waves of short wavelength in the range of …………… a) 0.5 A o to 10 A o b) 0.5 A o to 100 A o c) 0.5 A o to 1000 A o d) 10 A o to 100 A o

CHOOSE THE CORRECT ANSWER 47. Roentgen was awarded Nobel prize in 1901 for the discovery of ……………. a) gamma b) UV c) beta d) X-rays

CHOOSE THE CORRECT ANSWER 48. When fast moving electrons are suddenly stopped by a metallic target, ……… are produced. a) gamma rays b) UV rays c) X-rays d) beta rays

CHOOSE THE CORRECT ANSWER 49. In Coolidge tube, a high potential of about …………… is applied between filament F and the target T. a) 10000 V b) 20000 V c) 60000 V d) 50000 V

CHOOSE THE CORRECT ANSWER 50. X-rays are of ……………. types. a) 3 b) 4 c) 2 d) 5

CHOOSE THE CORRECT ANSWER 51. X-rays having wavelength of 4Ao or above are called ……………… a) hard X –rays b) soft X – rays c) medium X – rays d) gamma rays

CHOOSE THE CORRECT ANSWER 52. X-rays having low wavelength in the order of 1Ao are called …………… a) hard X –rays b) soft X – rays c) medium X – rays d) gamma rays

CHOOSE THE CORRECT ANSWER 53. The penetrating power of hard X-rays is ……………. a) low b) very low c) high d) zero

CHOOSE THE CORRECT ANSWER 54. When X-rays fall on certain metals, they liberate ………………… a) protons b) photons c) electrons d) mesons

CHOOSE THE CORRECT ANSWER 55. To detect and measure the intensity of the X rays, ………………. chamber is used. a) Thomson b) Bohr c) ionization d) Dalton

CHOOSE THE CORRECT ANSWER 56. Any plane containing an arrangement of atoms is known as a …………… plane. a) lattice b) crystal c) metal d) molecular

CHOOSE THE CORRECT ANSWER 57. Laue experiment is used to produce diffraction in ………………... a) gamma b) UV c) beta d) X-rays

CHOOSE THE CORRECT ANSWER 58. Bragg’s law is ………………. a) 2d tanθ = λ b) d Sinθ = n λ c) 2d Sin θ = n λ d) 2d Cos θ = n λ

CHOOSE THE CORRECT ANSWER 59. Bragg’s spectrometer is used to measure the wavelength of …………… a) gamma b) UV c) beta d) X-rays

CHOOSE THE CORRECT ANSWER 60. The minimum wavelength of the radiation emitted in continuous X-ray spectra λ min = ……… a) 12400A o / V b) 1240 A o / V c) 124 A o / V d) 124000A o / V

CHOOSE THE CORRECT ANSWER 61. When an electron jumps from M shell to the K shell, it gives ………in the case of characteristic X-rays. a) Lβ line b) K β line c) Kα line d) Mβ line

CHOOSE THE CORRECT ANSWER 62. The frequency of the spectral line in the characteristic X-rays is directly proportional to the square of the atomic number of the element. This is called …………………. a) Moseley’s law b) Stokes’s law c) Newton’s law d) Planck’s law

CHOOSE THE CORRECT ANSWER 63. …………. has led to the discovery of new elements like technetium, hafnium etc. a) Planck’s law b) Stokes’s law c) Newton’s law d) Moseley’s law

CHOOSE THE CORRECT ANSWER 64. In normal population, the number atoms in the ground state is ………… than the excited state. a) smaller b) lesser c) greater d) lower

CHOOSE THE CORRECT ANSWER 65. In population inversion, the number atoms in the ground state is …………. than the excited state. a) higher b) lesser c) greater d) more

CHOOSE THE CORRECT ANSWER 66. The life time of atoms in the excited state is normally …………….. a) 10 -6 second b) 10 -3 second c) 10 -8 second d) 10 -10 second

CHOOSE THE CORRECT ANSWER 67. The life time of atoms in the metastable state is normally …………… a) 10 -6 second b) 10 -3 second c) 10 -8 second d) 10 -10 second

CHOOSE THE CORRECT ANSWER 68. A ruby is a crystal of ……………. , in which of Al +3 ions are replaced by Cr +3 ions. a) P 2 O 5 b) Al 2 O 6 c) Al 2 O 2 d) Al 2 O 3

CHOOSE THE CORRECT ANSWER 69. The wavelength of green colour is …………… a) 7500 A o b) 5500 A o c) 6943 A o d) 6328A o

CHOOSE THE CORRECT ANSWER 70. The wavelength of red colour is ……………… a) 7500 A o b) 5500 A o c) 6943 A o d) 6328A o

CHOOSE THE CORRECT ANSWER 71. He-Ne laser system consists of a quartz discharge containing helium and neon in the ratio of ….. at a pressure of about 1 mm of Hg. a) 4 : 1 c) 1 : 4 b) 1 : 2 d) 2 : 1

CHOOSE THE CORRECT ANSWER 72. The wavelength of the emitted photon in the He-Ne laser system …………….. a) 7500 A o b) 5500 A o c) 6943 A o d) 6328A o

CHOOSE THE CORRECT ANSWER 73. The beam that is used in endoscopy is ………… a) laser b) maser c) ordinary light d) microwaves

CHOOSE THE CORRECT ANSWER 74. The beam that is used in holography is ……… a) laser b) maser c) ordinary light d) microwaves

CHOOSE THE CORRECT ANSWER 75. The ……… action is based on the principle of population inversion followed by stimulated emission. a) laser b) maser c) ordinary light d) microwaves

CHOOSE THE CORRECT ANSWER 76. The ……………. ions are used as maser materials. a) diamagnetic b) paramagnetic c) ferromagnetic d) aluminum

CHOOSE THE CORRECT ANSWER 77. Practical maser materials are often ……………. ions doped as impurities in ionic crystals. a) chromium b) sodium c) potassium d) calcium

CHOOSE THE CORRECT ANSWER 78. ……………. is used in molecular spectroscopy. a) laser b) maser c) ordinary light d) microwaves

CHOOSE THE CORRECT ANSWER 79. In optical fiber, ……………. laser is used. a) metal b) non-conducting c) semiconductor d) optical

CHOOSE THE CORRECT ANSWER 80. The ratio of the radii of the first three orbits of an atom is …………… a) 1 : 2 : 3 b) 1 : 3 : 5 c) 1 : 4 : 9 d) 1: 3 : 9

CHOOSE THE CORRECT ANSWER 81. The cathode rays are a stream of ……………. a) protons b) photons c) electrons d) mesons

CHOOSE THE CORRECT ANSWER 82. According to Bohr’s postulates, ……………. quantity take discrete values. a) energy b) momentum c) radius d) angular momentum

CHOOSE THE CORRECT ANSWER 83. For hydrogen atom, the minimum energy required to remove an electron from the first orbit to the outermost orbit is …………. eV. a) 13.6 b) 10.2 c) 5.4 d) infinity

CHOOSE THE CORRECT ANSWER 84. According to Rutherford atom model, atoms will give only …………… spectrum. a) continuous b) line c) band d) line absorption

CHOOSE THE CORRECT ANSWER 85. The elliptical orbits of electron in the atom were proposed by ……………. a) Thomson b) Somerfield c) Roentgen d) Huygens

CHOOSE THE CORRECT ANSWER 86. X ray is the phenomenon of conversion of kinetic energy into …………… a) radiation b) potential energy c) magnetic d) electrostatic energy

CHOOSE THE CORRECT ANSWER 87. The chromium ions doped in the ruby rod absorbs …………… light. a) red b) blue c) green d) yellow

CHOOSE THE CORRECT ANSWER 88. Canal rays travel …………. than the cathode rays. a) slower b) faster c) higher speed d) none of the above

CHOOSE THE CORRECT ANSWER 89. The spectra of alkali metals such as K, Na etc cannot be explained by ……………. atom model. a) Thomson b) Somerfield c) Roentgen d) Huygens

CHOOSE THE CORRECT ANSWER 90. In laser, all the photons are in …………. with each other. a) phase b) face c) pace d) base

CHOOSE THE CORRECT ANSWER 91. The cathode rays are (a) a stream of electrons (b) a stream of positive ions (c) a stream of uncharged particles (d) the same as canal rays

CHOOSE THE CORRECT ANSWER 92. A narrow electron beam passes undeviated through an electric field E = 3 × 104 V/m and an overlapping magnetic field B = 2×10−3 Wb/m2. The electron motion, electric field and magnetic field are mutually perpendicular. The speed of the electron is (a) 60 ms−1 (b) 10.3 × 107 ms−1 (c) 1.5 × 107 ms−1 (d) 0.67 × 10−7 ms−1

CHOOSE THE CORRECT ANSWER 93. According to Bohr’s postulates, which of the following quantities take discrete values?

(a) kinetic energy (b) potential energy (c) angular momentum (d) momentum

CHOOSE THE CORRECT ANSWER 94. The ratio of the radii of the first three Bohr orbit is, (a) 1 : 1/2 : 1/3 (b) 1 : 2 : 3 (c) 1 : 4 : 9 (d) 1 : 8 : 27

CHOOSE THE CORRECT ANSWER 95. The first excitation potential energy or the minimum energy required to excite the atom from ground state of hydrogen atom is, (a) 13.6 eV (b) 10.2eV

(c) 3.4 eV (d) 1.89 eV

CHOOSE THE CORRECT ANSWER 96. According to Rutherford atom model, the spectral lines emitted by an atom is, (a) line spectrum (b) continuous spectrum (c) continuous absorption spectrum (d) band spectrum

CHOOSE THE CORRECT ANSWER 97. Energy levels A, B, C of a certain atom correspond to increasing values of energy (i.e.,) E A < E B < E C . If λ 1 , λ 2 , λ 3 are the wavelengths of radiations corresponding to the transitions C to B, B to A and C to A respectively, which of the following statements is correct.

(a) λ 3 = λ 1 + λ 2 (b)

 3   1  1   2  2

(c) λ 1 = λ 2 + λ 3 = 0 (d) λ 2 3 = λ 2 1 + λ 2 2

CHOOSE THE CORRECT ANSWER 98. The elliptical orbits of electron in the atom were proposed by (a) J.J.Thomson

(b) Bohr (c) Sommerfeld (d) de Broglie

CHOOSE THE CORRECT ANSWER 99. X−ray is (a) phenomenon of conversion of kinetic energy into radiation.

(b) conversion of momentum (c) conversion of energy into mass (d) principle of conservation of charge

CHOOSE THE CORRECT ANSWER 100. In an X-ray tube, the intensity of the emitted X−ray beam is increased by (a) increasing the filament current (b) decreasing the filament current (c) increasing the target potential (d) decreasing the target potential

CHOOSE THE CORRECT ANSWER 101. The energy of a photon of characteristic X ray from a Coolidge tube comes from (a) the kinetic energy of the free electrons of the target (b) the kinetic energy of ions of the target (c) the kinetic energy of the striking electron (d) an atomic transition in the target.

CHOOSE THE CORRECT ANSWER 102. A Coolidge tube operates at 24800 V. The maximum frequency of X-radiation emitted from Coolidge tube is (a) 6 × 10 18 Hz (b) 3 × 10 18 Hz (c) 6 × 10 8 Hz (d) 3 × 10 8 Hz

CHOOSE THE CORRECT ANSWER 103. In hydrogen atom, which of the following transitions produce a spectral line of maximum wavelength (a) 2 → 1 (b) 4 → 1 (c) 6 → 5 (d) 5 → 2

CHOOSE THE CORRECT ANSWER 104. In hydrogen atom, which of the following transitions produce a spectral line of maximum frequency (a) 2 → 1 (b) 6 → 2 (c) 4 → 3 (d) 5 → 2

CHOOSE THE CORRECT ANSWER 105. After pumping process in laser, (a) the number of atoms in the ground state is greater than the number of atoms in the excited state.

(b) the number of atoms in the excited state is greater than the number of atoms in the ground state.

(c) the number of atoms in the ground state is equal to the number atoms in the excited state.

(d) No atoms are available in the excited state.

CHOOSE THE CORRECT ANSWER 107. The chromium ions doped in the ruby rod (a) absorbs red light (b) absorbs green light (c) absorbs blue light (d) emits green light