⭐ Electricity & Magnetism – Important GK for Students (Detailed Explanations + 100 Q&A)

(1500+ words, SEO-optimized)

Electricity and Magnetism together form one of the most essential chapters of Physics for competitive exams like SSC, Railway, Banking, UPSC, NDA, CDS, State PSC, NTPC, and all school-level examinations. Every year multiple questions are asked from electric charge, electric current, resistance, magnetism, electromagnetism, transformers, and electrical applications.

This article explains the concepts in a simple manner and provides 50 most important GK questions with answers.

🔌 What is Electricity?

Electricity is the flow of electric charge. These electric charges are usually carried by electrons moving through a conductor (like copper wire). Electric current powers almost every modern device—lights, fans, motors, computers, mobile chargers, etc.

🧲 What is Magnetism?

Magnetism is a force produced by moving electric charges. Magnets have two poles—North and South—and opposite poles attract, while like poles repel. When electricity and magnetism work together, they form Electromagnetism, the backbone of motors, generators, transformers, and modern electronics.

⭐ Important Terms in Electricity

1. Electric Charge

• Two types: positive and negative

• Like charges repel, opposite charges attract.

• Unit: Coulomb (C)

2. Electric Current

• Flow of electric charge per unit time

• Unit: Ampere (A)

• Measured by: Ammeter

3. Potential Difference (Voltage)

• Electrical “pressure” that pushes current

• Unit: Volt (V)

• Measured by: Voltmeter

4. Resistance

• Opposition to current

• Unit: Ohm (Ω)

• High resistance slows current.

5. Ohm’s Law

V = I × R
(Voltage = Current × Resistance)

⭐ Important Terms in Magnetism

1. Magnetic Field

• Space around a magnet where magnetic force acts.

2. Electromagnet

• Magnet created using electric current.

• Used in cranes, MRI machines, electric bells.

3. Magnetic Induction

• Making a material magnetic by another magnet.

4. Electromagnetic Induction

• Discovered by Michael Faraday

• Electricity produced by changing magnetic fields.

• Principle of generators, transformers, induction stoves.

⭐ Applications of Electricity & Magnetism

• Electric motors

• AC & DC generators

• Transformers

• Electric bell

• Fans, mixers, washing machines

• MRI machines

• Magnetic data storage devices

• Charging devices

• Speakers & microphones

⭐ Difference Between Electricity & Magnetism

🎯 50 Electricity & Magnetism Important GK Questions (With Answers & Explanations)

1. What is the SI unit of electric charge?

Answer: Coulomb
Explanation: Charge is the property of matter that causes electric force.

2. What is the SI unit of electric current?

Answer: Ampere
Explanation: It represents 1 Coulomb of charge passing per second.

3. Which instrument measures electric current?

Answer: Ammeter
Explanation: Connected in series in a circuit.

4. Which instrument measures voltage?

Answer: Voltmeter
Explanation: Always connected in parallel.

5. Who discovered the relationship between voltage, current, and resistance?

Answer: Georg Simon Ohm
Explanation: Ohm’s Law: V = IR.

6. What is the SI unit of resistance?

Answer: Ohm (Ω)

7. What is the unit of electrical power?

Answer: Watt
Explanation: 1 watt = 1 joule per second.

8. Which scientist discovered electromagnetic induction?

Answer: Michael Faraday
Explanation: Fundamental principle of generators & transformers.

9. What is an electromagnet?

Answer: A magnet created by electric current.
Example: Used in cranes to lift heavy metal.

10. Which gas is filled in modern bulbs?

Answer: Argon
Explanation: Prevents oxidation of filament.

11. What is the SI unit of magnetic field?

Answer: Tesla
Explanation: Strongest magnetic fields measured in Tesla.

12. What is the unit of magnetic flux?

Answer: Weber

13. Who discovered the electron?

Answer: J.J. Thomson

14. Which particle carries electric charge in metals?

Answer: Electron
Explanation: Free electrons flow in conductors.

15. What is the direction of magnetic field in a straight conductor?

Answer: Circular around the wire (Right-hand thumb rule).

16. Which device converts mechanical energy into electrical energy?

Answer: Generator
Explanation: Based on electromagnetic induction.

17. Which device converts electrical energy into mechanical energy?

Answer: Motor
Explanation: Based on Fleming’s left-hand rule.

18. What is the function of a transformer?

Answer: Steps voltage up or down.

19. What current is used in homes?

Answer: Alternating Current (AC)

20. Who invented the electric bulb?

Answer: Thomas Alva Edison

21. Why do electric wires have plastic coating?

Answer: Plastic is an insulator.

22. What is short circuit?

Answer: When current flows directly with low resistance → sparks/fire risk.

23. What prevents short circuits in homes?

Answer: Fuse or Miniature Circuit Breaker (MCB).

24. What is earthing?

Answer: Connecting appliances to the ground for safety.

25. What material is used for earthing?

Answer: Copper or iron rods.

26. Which current flows in battery?

Answer: DC (Direct Current)

27. Which current flows in home supply?

Answer: AC (Alternating Current)

28. What is electric fuse made of?

Answer: Tin-lead alloy
Explanation: Low melting point.

29. What is magnetic declination?

Answer: Angle between magnetic north and geographic north.

30. Why do magnets have two poles?

Answer: Magnetic domains align in one direction.

31. Can a magnet have only one pole?

Answer: No
Explanation: Cutting a magnet always produces two poles.

32. Which metal is most magnetic?

Answer: Iron (Fe)

33. Which material is used to make magnets?

Answer: Iron, nickel, cobalt

34. What is Fleming’s right-hand rule used for?

Answer: Generator working principle.

35. What is Fleming’s left-hand rule used for?

Answer: Motor working principle.

36. What produces a magnetic field in a coil?

Answer: Electric current.

37. What increases the strength of an electromagnet?

Answer:

• More current

• More turns in coil

• Soft iron core

38. Why is soft iron used in electromagnets?

Answer: Easily magnetized & demagnetized.

39. What is a solenoid?

Answer: A long coil of wire acting like a magnet.

40. What phenomena makes compasses work?

Answer: Earth’s magnetic field.

41. What type of current does transformer work on?

Answer: AC
Explanation: Only AC creates changing magnetic fields.

42. What is an electric circuit?

Answer: Path for electric current.

43. What is conductor?

Answer: Material that allows electricity.
Examples: Copper, aluminum

44. What is insulator?

Answer: Material that resists electricity.
Examples: Plastic, rubber

45. Which battery is used in cars?

Answer: Lead-acid battery.

46. What is capacitor used for?

Answer: Storing electrical charge.

47. What is induction?

Answer: Production of electricity by magnetic field.

48. What is the magnetic field inside a solenoid?

Answer: Uniform and parallel.

49. Which scientists proved electricity creates magnetism?

Answer: Hans Christian Ørsted.

50. What is an electric bell based on?

Answer: Electromagnet.

51. What is the SI unit of electric potential?

Answer: Volt
Explanation: Potential difference measures electrical pressure.

52. What is electric power?

Answer: Rate of doing electrical work
Formula: P = VI

53. What is the resistance of a conductor dependent on?

Answer:

• Length

• Area

• Temperature

• Material type

54. What is the unit of energy used in electricity bills?

Answer: kWh (kilowatt-hour)
Explanation: 1 kWh = 1 unit of electricity.

55. What is a rheostat used for?

Answer: Controlling current
Explanation: By changing resistance.

56. What is the unit of capacitance?

Answer: Farad (F)

57. What type of current does a battery supply?

Answer: Direct Current (DC)

58. What type of current does a generator supply?

Answer: AC or DC (depending on type)

59. Which wire carries current in a household circuit?

Answer: Live wire
Colour: Red/Brown

60. Which wire ensures safety from leakage?

Answer: Earth wire
Colour: Green

61. What is a magnetic compass used for?

Answer: To show direction using Earth’s magnetic field.

62. What is the main function of a fuse?

Answer: To protect the circuit from overload.

63. What type of material is used to make fuse wire?

Answer: Tin + lead alloy

64. What is electromagnetic wave?

Answer: Wave produced by oscillating electric and magnetic fields.

65. Does electromagnetic wave need a medium?

Answer: No, it travels in vacuum.

66. What is Lenz’s law?

Answer: Induced current opposes the change that produced it.

67. Who discovered Lenz’s law?

Answer: Heinrich Lenz

68. What happens when you increase the temperature of a conductor?

Answer: Resistance increases.

69. What happens when you increase the temperature of a semiconductor?

Answer: Resistance decreases.

70. Which metal has the lowest resistivity?

Answer: Silver

71. Which device stores electrical energy in an electric field?

Answer: Capacitor

72. What is induction coil?

Answer: Device used to produce high voltage from low voltage.

73. What does a transformer NOT work with?

Answer: DC current
Explanation: DC doesn’t create changing magnetic field.

74. What is alternating current frequency in India?

Answer: 50 Hz

75. What is the frequency of DC?

Answer: 0 Hz (no oscillation)

76. What is electromotive force (EMF)?

Answer: Voltage generated by battery or generator.

77. What is magnetic moment?

Answer: Strength of a magnet.

78. What is a galvanometer used for?

Answer: Detecting small currents.

79. What is a diode?

Answer: Device that allows current in one direction only.

80. Which device converts AC to DC?

Answer: Rectifier

81. Which device converts DC to AC?

Answer: Inverter

82. Why is copper used in wires?

Answer: Low resistance + high conductivity.

83. Why is aluminium sometimes used instead of copper?

Answer: Cheaper and lightweight.

84. Why is tungsten used in bulbs?

Answer: High melting point.

85. Why does a bulb glow?

Answer: Due to heating effect of electric current.

86. What is magnetic susceptibility?

Answer: Degree to which a material becomes magnetized.

87. What is dia-magnetic material?

Answer: Material repelled by magnetic field.
Examples: Copper, gold, water.

88. What is para-magnetic material?

Answer: Weakly attracted by magnets.
Examples: Aluminium, platinum.

89. What is ferro-magnetic material?

Answer: Strongly attracted by magnets.
Examples: Iron, cobalt, nickel.

90. What is the Earth’s magnetic field called?

Answer: Geomagnetic field.

91. Which phenomenon makes the electric motor work?

Answer: Magnetic force on current-carrying conductor.

92. What is eddy current?

Answer: Circular currents induced in metal plates.

93. Where is eddy current used?

Answer:

• Induction stoves

• Braking systems

• Energy meters

94. Full form of LED?

Answer: Light Emitting Diode

95. Full form of CFL?

Answer: Compact Fluorescent Lamp

96. What does a battery contain?

Answer: Electrochemical cells to produce DC.

97. What happens if resistance becomes zero?

Answer: Short circuit occurs.

98. What force acts on a moving charge in a magnetic field?

Answer: Lorentz force

99. Who discovered that current-carrying wire produces magnetic field?

Answer: Hans Christian Ørsted

100. What is principle of electric generator?

Answer: Electromagnetic induction.

⭐ You now have 100 Electricity & Magnetism GK Questions

Perfect for a 3000+ word SEO article on GK Bunch that ranks extremely well.

⭐ Conclusion

Electricity and Magnetism are the foundation of modern physics and technology. Understanding the core concepts—current, voltage, resistance, circuits, magnetic fields, electromagnetism—helps students perform better in exams and real-life applications.