PGTRB:LATEST STUDY MATERIAL: PHYSICS: ATOMIC PHYSICS. - Tamil Crowd (Health Care)

PGTRB:LATEST STUDY MATERIAL: PHYSICS: ATOMIC PHYSICS.

👍👍👍 PGTRB:LATEST STUDY MATERIAL: 

PHYSICS: 

ATOMIC PHYSICS.

1)Electrons was discovered by J.J.Thomson.

2)X-rays was discovered by Roentgen.

3)A discharge tube is an arrangement to the conduction of electricity through gases.

4)Discharge of electricity through gases led to the discovery of electrons.

5)At pressure of about 110mm of Hg, no disc occurs through the tube.

6)At the pressure of about 10mm of Hg the irregular streaks broaden out a luminous column extending from anodes almost upto cathode is known as positive column.

7)Cathode rays travel in straight line.

8)Cathode rays possess momentum and kinetic energy.

9)When cathode rays strike a solid substance of large atomic weight, X-rays are produce.

10)Cathode rays ionize the gas through which they pass.

11)Cathode rays affect the photographic plate.

12)The cathode rays are deflected from the straight line path by both electric and magnetic field.

13)Cathode rays travel with a velocity upto (1/10)th of the velocity of light.

14)Cathode rays comprises of electron which are fundamental constituents of all atom.

15)An atom is said to be in ground state when its energy is least.

16)Before an atom can emit spectral radiation the electron in it has to be raised to a higher orbit and the process is known as excitation of the atom.

17)The energy required to raise an atom from its normal state into an excited state is called excitation potential energy of the atom.

18)The potential corresponding to excitation energies are called as the excitation potential.

19)The excitation potential and ionization potential are called as the critical potential of the atom.

20)The critical potential of an atom is define as the minimum potential required to excite a free neutral atom from its ground state to higher state.

21)Franck and Hertz performed series experiments to measure the excitation potential of different elements.

22)Bohr theory could not account for the spectra of atoms more complex than hydrogen.

23)Bohr theory does not give any information regarding the distribution and arrangement of electrons in an atom.

24)Bohr’s theory could not account for fine structure of spectral lines.

25)In Sommerfeld theory, the path of an electron around the nucleus is an ellipse with nucleus at one of to foci.

26)According to Sommerfeld, the velocity of the electron is maximum when the electron to the nucleus and minimum when it is farther from the nucleus, since the orbit of electron is elliptical.

27)Sommerfeld modification could not predict the correct number of observed fine structure of these lines.

28)Sommerfeld could not explain the distribute and arrangement of electron in atoms.

29)Summerfield’s model was unable to explain the spectra of alkali metals such as sodium, potassium etc.,

30)Sommerfeld could not explain Zeeman effect and stark effect.

31)Sommerfeld does not give any explanation for the intensities of the spectral lines.

32)According vector atom model, the orientation direction, of the orbits in space should be quantized.

33)The introduction of such a spatial quantization does not change the size or shape of the Bohr-Sommerfeld’s orbit but makes the one’s vector quantities.

34)According to vector atom model, electron has two types of motion (i) orbital motion (ii) spin motion.

35)The orbital and spin motions are quantized not only in magnitude but also in direction according to the concept of spatial quantized.

36)The fundamental postulates of vector atom model have been experimentally verified by Stern and Gerlach.

37)If one electron in an atom occupies a completely defined quantum  state, any other  electron in the atom is strictly exclude from occupying that quantum state.

38)Pauli’s exclusion principle helps us in calculate the number of permitted electrons in varies sub-shell and hence in various shells.

39)Mendeleev arranged the elements on their chemical properties and atomic weight.

40)Mostly arranged the elements the increasing order pf atomic weight.

41)The charge of an electron was found to be 1.602*10^-19 coulomb.

42)Periodic table of elements by mostly consists of seven horizontal rows called periods and eight vertical columns called groups.

43)The cathode in the Coolidge tube is tungsten filament and is heated by passing a current through it from a low tension battery.

44)The electrons are emitted by the process of thermionic emission from the cathodes.

45)The tungsten filament is surrounded by molybdenum cylinder kept at a negative potential to the filaments.

46)The anode of the Coolidge tube should have the high atomic weight, high melting points and high thermal conductivity.

47)The wavelength of X-rays depends upon kinetic energy of the electrons producing them and this kinetic energy depends the potential difference between the filaments and the target.

48)X-rays travel in straight line with velocity of light.

49)X-rays are not deflected by electric and magnetic fields and do not have charge particles.

50)X-rays undergo reflection, refraction, interference, diffraction and polarization.

51)X-rays affect photographic plates.

52)X-rays can penetrate through the substance which are opaque to ordinary light.(eg):thick paper, thin sheets of metals.

53)Hard x-rays are used to destroy tumors very deep inside the body.

54)X-rays are also used to study the structure of materials like rubber, cellulose, plastic fiber.

55)X-rays are used to analyse the structure of alloys and the other composite bodies.

56)X-rays can be used for testing the homogeneity of welded joints, insulating materials etc.,

57)x-rays are used to detect the defects flows within a material.

58)X-rays are used for studying the structure of crystalline solids and all.

59)X-rays are used for the identification of chemical elements including determination of their atomic numbers.

60)Light emitted from ordinary light source is incoherent.

61)LASER: Light Amplification by Stimulated Emission of Radiations.

62)Laser is used in Raman Spectroscopy.

63)Laser beams in used in holography.

64)Earth – moon distance has been measure with the help of lasers.

65)Narrow angular spread of the laser beam makes it a very useful tool for microwave communication.

66)Semiconductor laser is the best light source for optical fiber communication.

67)Laser is used in the treatment of human and animal cancer.

68)Laser can be modulated to transmit large number of message at a time in radian, television and telescope.

69)A three dimensional image of a object can be formed by holography.

70)In holography both the phase and amplitude  of the light resulting photograph is called hologram.

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