Electrostatics

Physics, SSC-KPK Class 10. This chapter is split into 61 topics and has 1,577 practice questions. The topics covered are listed below, followed by 10 free sample questions from the chapter.

Topics in this chapter

1. Electric field of a point charge 30 questions
2. Series combination of capacitors - theory 22 questions
3. Electrification by rubbing and charge transfer 22 questions
4. Coulomb's law statement and formula 21 questions
5. Capacitor and capacitance 27 questions
6. Finding an unknown charge from the force 28 questions
7. Coulomb force in a medium and permittivity calculations 26 questions
8. Unit 13 key points and learning outcomes 23 questions
9. Three or more capacitors in parallel 28 questions
10. Motion of electrons and protons in an electric field 26 questions
11. Work in moving a charge between two potentials 28 questions
12. Changes in Coulomb force when charges or distance change 30 questions
13. Series versus parallel capacitors - comparison 21 questions
14. Unit 13 conceptual questions 23 questions
15. Coulomb force between charges in nanocoulomb 28 questions
16. Electrostatic precipitator and electro-painting 22 questions
17. Three or more capacitors in series 30 questions
18. Electric field intensity from force and test charge 30 questions
19. Coulomb force between charges in millicoulomb and metre 26 questions
20. Coulomb force inside atoms and nuclei 28 questions
21. Positive and negative work and direction of potential 20 questions
22. Force on a charge in a uniform electric field 30 questions
23. Voltage across a capacitor from charge and capacitance 28 questions
24. Electric potential and the volt 24 questions
25. Two capacitors in series - equivalent capacitance 30 questions
26. Charge stored on a capacitor from capacitance and voltage 28 questions
27. Unknown capacitor in a series combination 26 questions
28. Coulomb force between charges in microcoulomb and centimetre 30 questions
29. Energy gained by charged particles through a potential difference 24 questions
30. Unknown capacitor in a parallel combination 26 questions
31. Identical capacitors in series and parallel groups 28 questions
32. Types of capacitors and their uses 24 questions
33. Coulomb's constant and permittivity 20 questions
34. Point charge field: distance, charge and scaling 30 questions
35. Electric field and electric field intensity 23 questions
36. Series-parallel capacitor networks (parallel pair in series with a third) 30 questions
37. Charge and voltage in series combinations 30 questions
38. Work done by moving small charges through a potential difference 30 questions
39. Basic charges of atoms and elementary charge 28 questions
40. Coulomb's law compared with Newton's law of gravitation 20 questions
41. Charge sharing between identical spheres 30 questions
42. Electric charge and the two kinds of charge 23 questions
43. Potential from work and charge 28 questions
44. Unit 13 exercise multiple choice questions 21 questions
45. Work done on charges given in coulomb 30 questions
46. Electrostatic induction 21 questions
47. Electroscope 22 questions
48. Parallel combination of capacitors - theory 21 questions
49. Voltage across capacitors in a three-capacitor series chain 28 questions
50. Charge and voltage in parallel combinations 30 questions
51. Capacitor exercises from Unit 13 numerical problems 24 questions
52. Parallel-series capacitor networks (series pair in parallel with a third) 30 questions
53. Lightning and the danger of static charge 20 questions
54. Finding the separation of charges from the force 30 questions
55. Electric field lines 21 questions
56. Lightning conductors and safety during thunderstorms 20 questions
57. Capacitance from charge and voltage 28 questions
58. Finding the amount of charge from work and potential difference 24 questions
59. Two capacitors in parallel - equivalent capacitance 24 questions
60. Finding a charge from force and field intensity 26 questions
61. Nature and magnitude of the force between two charges 28 questions

Sample questions: Electrostatics

10 sample questions with the correct answer and an explanation. Try to answer each one before reading the explanation.

Q1. We feel a shock when touching a metal doorknob after walking across a synthetic carpet because

• A. the doorknob is always positively charged
• B. the carpet has produced a current from heat
• C. charge built up on the body is suddenly discharged(correct answer)
• D. the doorknob has become magnetic

Answer: C.Walking on a carpet charges the body; the stored charge jumps to the metal doorknob, which we feel as a shock (electrostatic force in action).

Q2. A negatively charged ball is brought near a suspended rod and they attract. The rod may be

• A. positively charged(correct answer)
• B. negatively charged
• C. only a negative conductor
• D. unable to be charged

Answer: A.Attraction between charged bodies indicates opposite charges (a neutral object could attract too, but of the options only a positive rod is consistent with attraction between charges).

Q3. In testing a charged object, a neutral object brought near an electroscope charged earlier will

• A. always collapse the leaves fully
• B. make the electroscope neutral
• C. always diverge the leaves to 90°
• D. cause little or no change(correct answer)

Answer: D.A neutral object produces no net effect on the electroscope (it can only produce a small effect through induction in nearby conductors).

Q4. Electric field lines are drawn so that they

• A. are always parallel to each other at each point
• B. follow the direction of the field vector at each point(correct answer)
• C. are always at right angles to the field at each point
• D. always form closed circles around each charge

Answer: B.An easy way to visualize a field is to draw lines that follow the same direction as the electric field intensity vector E at any point.

Q5. The potential at a point defined by V = W/q means that W is

• A. the heat produced in the charge while moving
• B. the kinetic energy of q while at infinity
• C. the work done against the field to bring q from infinity(correct answer)
• D. the work done by the field on q leaving that point

Answer: C.In equation 13.5 V is by definition the work that must be done against the field to bring a test charge q from infinity to a specific location.

Q6. The tip on the lightning conductor says that its function is also to avoid

• A. the formation of rain from the clouds
• B. the formation of thunderclouds in the sky
• C. the damage of the strike itself and the associated current(correct answer)
• D. the formation of strong winds near the building

Answer: C.By catching the lightning and running the discharge current to earth, they avoid damage connected with the strike itself and the circulation of the associated current.

Q7. Why does a capacitor have a maximum voltage?

• A. above it the field causes dielectric breakdown and a spark(correct answer)
• B. above it the charge is always limited to exactly 1 C
• C. above it the battery cannot supply any more charge
• D. above it the plates melt as soon as the voltage is applied

Answer: A.If overfilled, the field between plates becomes so strong that dielectric breakdown occurs, causing a spark and destroying the capacitor.

Q8. If two insulating plates were used instead of conducting plates in a capacitor,

• A. there would be no change in the capacitor at all
• B. charge could not spread over them, so very little would be stored(correct answer)
• C. the capacitor would charge much faster than before
• D. the capacitance would become much greater than before

Answer: B.Insulators keep charge where it was placed and so do not carry charges uniformly; conducting plates are required to hold charge on the surface.

Q9. During a heart attack the heart produces a rapid, unregulated pattern of beats called

• A. cardiac arrest only
• B. hypertension
• C. blood clotting
• D. cardiac fibrillation(correct answer)

Answer: D.The condition is known as cardiac fibrillation, which can often be stopped by a fast discharge of electrical energy through the heart.

Q10. Key point: a capacitor is

• A. a device used for producing heat from current
• B. a source of steady current in a circuit
• C. a device used for measuring voltage in a circuit
• D. a device used for storing electrical energy (charge)(correct answer)

Answer: D.The key points call a capacitor the device used for storing electrical energy; in the text it is described as a charge-storing device.