UNIT 5 ATOMIC PHYSICS QUESTIONS Chapter 17 Introduction to Atomic Physics One mark questions 1. Name the method to determine e/m. 2. Define specific charge of an electron. 3. Why line emission spectrum is also known as atomic spectrum? 4. State Kirchoff’s law of radiation. 5. What is an electromagnetic spectrum? 6. What is the natural source of UV radiation. Two mark questions 7. Write condition for the electron to pass through the three slits in Dunnington’s experiment. Chapter 18 Photoelectric Effect One mark questions 8. What is the SI unit of work function? 9. What is the principle of photoconductive cell? Two mark questions 10. Write the Einstein’s photoelectric equation. 11. Write the relation between maximum kinetic energy and stopping potential. 12. Write the relation between work function and threshold wavelength. 13. Maximum kinetic energy of photoelectrons emitted by a surface is 16
stopping potential. Chapter 19 Dual Nature of Matter One mark questions 10
. Calculate the 14. An electron and an alpha particle are moving with the same velocity. Which one is associated with matter wave of longer wavelength? 15. Two particles A and B have the same mass. A is moving with a velocity twice that of B. Which one of the two particles is associated with matter wave of shorter wavelength? 16. What is the principle of G.P. Thomson’s experiment? 17. What is the principle of electron microscope? Chapter 20 Bohr’s Atom Model One mark questions 18. What are stationary orbits? 19. What are the factors on which the radius of the orbit of any hydrogen like atom depends? 20. If r is the radius of the first orbit of a hydrogen atom, then what is the radius of the first orbit of helium atom? 21. What is Bohr radius? 22. What is the value of Bohr radius? 23. How does the velocity of an electron change with the change in the number of the orbit? 24. How is the velocity of an electron related to the atomic number of the atom? 25. What are the factors on which the velocity of an electron depends? 26. If the velocity of an electron in the first orbit of hydrogen atom is v, then what is the velocity of an electron in the second orbit in terms of v? 27. What is the significance of negative sign in the expression for energy of an electron in an orbit? 28. How does the energy of an electron change with the change in the atomic number of the atom? 29. How is the energy of an electron related to the number of the orbit? 30. What is wave number of a spectral line? 31. What is the value of Rydberg constant? 32. What is series limit? 33. Name any one of the main features of vector atom model. Two mark questions 34. Write Bohr’s quantization rule and explain the terms. 35. Write Bohr’s frequency condition and explain the terms. 36. Write down the expression for the radius of the nth orbit of hydrogen like atom. 37. Write down the expression for the radius of the nth orbit of hydrogen atom. 38. Radius of the second orbit of lithium atom is 0.70
fourth orbit of lithium atom? 10
. What would be the radius of the 39. Radius of the second orbit of lithium atom is 0.70
second orbit of helium atom? 10
. What would be the radius of the 40. Write down the expression for the orbital velocity of an electron in the nth orbit of hydrogen like atom. 41. Write down the expression for the orbital velocity of an electron in the nth orbit of hydrogen atom. 42. Using Bohr’s postulates arrive at an expression for the orbital velocity of hydrogen like atom. 43. Write down the expression for total energy of an electron in an orbit of hydrogen atom. 44. Give the expression for the wave number of spectral series of hydrogen atom. 45. Write the expression for Rydberg constant. 46. What are the two suggestions made by Sommerfeld to overcome the problem of fine structure of hydrogen spectrum? Chapter 21 Scattering of Light One mark questions 47. State Rayleigh’s law of scattering. 48. How is the intensity of scattered light related to the wavelength of light? 49. What are Raman lines? 50. What are Raman lines? 51. What type of scattering is Raman effect? Two mark questions 52. Distinguish between coherent and incoherent scattering of light. 53. Name any two applications of Raman effect. 54. Distinguish between stokes and anti‐stokes lines. Chapter 22 Lasers One mark questions 54.What is the average life time of excited state of an atom?