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ELECTROSTATICS

Part 1:Theoritical questions: Test:7-4-13 time:5 hrs (1pm-6pm)

Alok shaw SELF STUDY QUESTION BANK

1. What do you mean by Electrostatics?2. Define electric charge?3. State the Fundamental law of electrostatics?4. Define the terms-Condutor and Insulator?5. What do you mean by-Electrostatic Induction?How it works with example?6. Write a short note on Gold-Leaf electroscope(working)?7. What do you mean by additive nature of electric charge?8. What do you mean by quantization of electric charge?Why it is quantized?9. Define-Law of conservation of charge,with suitable examples(at least two)?10. How does the electrical charged particle affects its (i)-Mass and (ii)Charge?11. State coulombs law and derive an expression for it and also,Vector form of coulombs law.12. What is electrostatics force constant?its SI unit and dimension?13. Define one coulomb ?14. Show that coulombs law follow Newton third law of motion?15. What do you mean by permittivity of a medium?16. Define dielectric constant in terms of forces between two charges?17. What is the similarity and dissimilarity betweenElectrostatic force and Gravitational force?18. How much is the electrostatic force stronger than the Gravitational force?Give two examples

which shows the E.F.>G.F.?

19. State the principle of Superposition of electrostatic forces.HenceWrite an expression for the forceon a point due to a distribution of n point charge in terms of their position vectors.

20. Define-Electric Field at a point,its unit and dimensions and state its significane.21. Obtain an expression for the electric field intensity at a point at a distance r from a charge q.What

is the nature of this field?

22. Deduce an expression for the electric field at a point due to a system of N point charges?23. What is a continuous charge distribution ? How can we calculate the force on a point charge q

due to a continuous charge distribution?

24. State three types of charge distribution?25. What is an electric dipole ?Define dipole moment and give its SI unit?What is ideal or point

dipoles?

26. What is a dipole field ?Why does the dipole field at large distance falls off faster than 1/r^2?27. Derive an expression for electric field at-28. any point on the axial line of an electric dipole29. point at the equatorial line of an electric dipole30. Give a comparison of the magnitude of electrical field of a short dipole at axial and equatorial

points?

31. Define an expression for the torque on an electric field. Hence define dipole moment?32. What happens,when an electric dipole is held in a non-uniformelectric field? What will be the force

and the torque when the dipole is held parallel or anti parallel to the electric field?

33. What are electric lines of force? Give their important properties.34. Draw the field lines of different charge system-

i. 1.positive point chargeii. 2.negative point charge

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iii. 3.two equal and opp. Chargeiv. 4.two similar charges.

35. what is the relation between the density of lines of force and electric field strength?36. What is an area vector? How can we specify the direction of plane area vector?37. Define the term electric flux. How is it related to electric field intensity?38. State and prove Gausss theorem.39. What is Gaussian surface. Give its importance.40. Deduce Coulombs law from Gausss theorem.41. Apply Gausss theorem to calculate the electric field-

i. 1.due to an infinite plane sheet of chargeii. 2.of a thin infinitely long straight line of charge of uniform density of lamda cm^-1.

42. When a glass rod is rubbed with silk, both acquire charges. What is the source of theirelectrification?

43. Two identical metallic spheres of exactly equal masses are taken. One is given a positive chargeqcoulombs and other an equal negative charge. Are their masses after charging equal?

44. How does positively charged glass rod attract a neutral piece of paper?45. Can two like charges attract each other? If yes, how46. Why do gramophone records get covered with dust easily?47. Electrostatic experiments do not work well on humid days. Give reason.48. A comb run through ones dry hair attract small bits of paper. Why? What happens ifthe hair is

wet or if it is a rainy day?

49. Ordinary rubber is an insulator. But the special rubber tyres of aircraft are made slightlyconducting. Why is this necessary?

50. Vehicles carrying inflammable materials usually have metallic ropes touching the ground duringmotion. Why?

51. And inflated balloon is charged by rubbing with fur. Will it stick readily to a conducting wall or toan insulating wall? Give reason.

52. A metal sphere is fixed on a smooth horizontal insulating plate. Another metal sphere is placed asmall distance away. If the fixed sphere is given a charge, how will the other sphere react?

53.Is there some way of producing high voltage on your body without getting shock?

54. Can a body have charge of 0.8x10-19C? Justify your answer by comment?55. If the distance between two equal point charges is doubled and their individual charges are also

doubled, what would happen to the force between them?

56. How is Coulomb force between two charges affected by the presence of third charge?57. How does the force between two point charges change, if the dielectric constant of the medium

in which they are kept, increases?

58. Why should a test charge be of negligibly small magnitude?59. In defining electric field due to a point charge, the test charge has to be vanishingly small. How

this condition can be justified, when we know that charge less than that on an electron or a

proton is not possible?

60. How do charges interact?61. An electron and a proton are kept in the same electric field. Will they experience same force and

have same acceleration?

62. Why direction of an electric field is taken outward (away) for a positive charge and inwards(toward) for a negative charge?

63. A charged particle is free to move in an electric field. Will it always move along an electric field?64. A small test charge is released at rest at a point in an electrostatic field configuration. Will is

travel along the line of force?

65. Why is electric field zero inside a charged conductor?

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66. Is charge uniformly distributed over the surface of an insulated conductor of any shape? If not,what is the rule for the distribution of charge over a conductor?

67. The electric lines of force tend to contract lengthwise and expand laterally. What do theyindicate?

68. A point charge placed at any point on the axis of an electric dipole at some large distanceexperiences a force F. What will be the force acting on the point charge when its distance from

the dipole is doubled?

69. What is the number of electric lines of force that radiate outwards from on coulomb of charge invaccum?

70. What is the electric flux through a closed surface enclosing an electric dipole?