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NCERT Solutions › Physics › Chapter 1

Chapter 1: Electric Charges & Fields

NCERT Solutions for CBSE Class 10 Physics — 105 solved questions with detailed explanations.

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Questions
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Solved Questions

Q1. Gauss's law relates the electric flux through a closed surface to the:

Difficulty: Easy · Topic: Gauss's Law

Solution

Gauss's law: Φ = q_enclosed/ε₀. The flux depends only on the enclosed charge.

Q2. The electric field inside a charged conducting sphere is:

Difficulty: Easy · Topic: Conductors

Solution

Inside a conductor, E = 0 in electrostatic equilibrium. All charge resides on the surface.

Q3. An electric dipole is placed in a uniform electric field. The net force on the dipole is:

Difficulty: Easy-Medium · Topic: Electric Dipole

Solution

In a uniform field, forces on +q and -q are equal and opposite. Net force = 0. Net torque = pE sinθ.

Q4. The force between charges 1μC and 1μC separated by 10 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r² = 9×10⁹×1×10⁻⁶×1×10⁻⁶/(0.1)² = 0.9 N.

Q5. The force between charges 2μC and 3μC separated by 30 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r² = 9×10⁹×2×10⁻⁶×3×10⁻⁶/(0.3)² = 0.6 N.

Q6. The force between charges 1μC and 4μC separated by 20 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r² = 9×10⁹×1×10⁻⁶×4×10⁻⁶/(0.2)² = 0.9 N.

Q7. The force between charges 2μC and 2μC separated by 10 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r² = 9×10⁹×2×10⁻⁶×2×10⁻⁶/(0.1)² = 3.6 N.

Q8. The force between charges 3μC and 3μC separated by 15 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r² = 9×10⁹×3×10⁻⁶×3×10⁻⁶/(0.15)² = 3.6 N.

Q9. Electric field at 10 cm from a 1μC charge is:

Difficulty: Easy-Medium · Topic: Electric Field

Solution

E = kq/r² = 9×10⁹×1×10⁻⁶/(0.1)² = 900000 N/C.

Q10. Electric field at 20 cm from a 2μC charge is:

Difficulty: Easy-Medium · Topic: Electric Field

Solution

E = kq/r² = 9×10⁹×2×10⁻⁶/(0.2)² = 450000 N/C.

Q11. Electric field at 10 cm from a 4μC charge is:

Difficulty: Easy-Medium · Topic: Electric Field

Solution

E = kq/r² = 9×10⁹×4×10⁻⁶/(0.1)² = 3600000 N/C.

Q12. Electric field at 5 cm from a 1μC charge is:

Difficulty: Easy-Medium · Topic: Electric Field

Solution

E = kq/r² = 9×10⁹×1×10⁻⁶/(0.05)² = 3600000 N/C.

Q13. Electric field at 30 cm from a 3μC charge is:

Difficulty: Easy-Medium · Topic: Electric Field

Solution

E = kq/r² = 9×10⁹×3×10⁻⁶/(0.3)² = 300000 N/C.

Q14. Force between charges 1μC and 2μC at 10 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q15. Force between charges 2μC and 3μC at 15 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q16. Force between charges 3μC and 4μC at 20 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q17. Force between charges 4μC and 5μC at 25 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q18. Force between charges 5μC and 6μC at 30 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q19. Force between charges 6μC and 7μC at 35 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q20. Force between charges 7μC and 8μC at 40 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q21. Force between charges 8μC and 9μC at 45 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q22. Force between charges 9μC and 10μC at 50 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q23. Force between charges 10μC and 11μC at 55 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q24. Force between charges 11μC and 12μC at 60 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q25. Force between charges 12μC and 13μC at 65 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q26. Force between charges 13μC and 14μC at 70 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q27. Force between charges 14μC and 15μC at 75 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q28. Force between charges 15μC and 16μC at 80 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q29. Force between charges 16μC and 17μC at 85 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q30. Force between charges 17μC and 18μC at 90 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q31. Force between charges 18μC and 19μC at 95 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q32. Force between charges 19μC and 20μC at 100 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q33. Force between charges 20μC and 21μC at 105 cm is:

Difficulty: Easy-Medium · Topic: Coulomb's Law

Solution

F = kq₁q₂/r².

Q34. F between 1μC and 1μC at 5cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=3.6 N.

Q35. F between 1μC and 1μC at 10cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.9 N.

Q36. F between 1μC and 1μC at 15cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.4 N.

Q37. F between 1μC and 1μC at 20cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.225 N.

Q38. F between 1μC and 1μC at 25cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.144 N.

Q39. F between 1μC and 1μC at 30cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.1 N.

Q40. F between 1μC and 2μC at 5cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=7.2 N.

Q41. F between 1μC and 2μC at 10cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=1.8 N.

Q42. F between 1μC and 2μC at 15cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.8 N.

Q43. F between 1μC and 2μC at 20cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.45 N.

Q44. F between 1μC and 2μC at 25cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.288 N.

Q45. F between 1μC and 2μC at 30cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.2 N.

Q46. F between 1μC and 3μC at 5cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=10.8 N.

Q47. F between 1μC and 3μC at 10cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=2.7 N.

Q48. F between 1μC and 3μC at 15cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=1.2 N.

Q49. F between 1μC and 3μC at 20cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.675 N.

Q50. F between 1μC and 3μC at 25cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.432 N.

Q51. F between 1μC and 3μC at 30cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.3 N.

Q52. F between 1μC and 4μC at 5cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=14.4 N.

Q53. F between 1μC and 4μC at 10cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=3.6 N.

Q54. F between 1μC and 4μC at 15cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=1.6 N.

Q55. F between 1μC and 4μC at 20cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.9 N.

Q56. F between 1μC and 4μC at 25cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.576 N.

Q57. F between 1μC and 4μC at 30cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.4 N.

Q58. F between 1μC and 5μC at 5cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=18.0 N.

Q59. F between 1μC and 5μC at 10cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=4.5 N.

Q60. F between 1μC and 5μC at 15cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=2.0 N.

Q61. F between 1μC and 5μC at 20cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=1.125 N.

Q62. F between 1μC and 5μC at 25cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.72 N.

Q63. F between 1μC and 5μC at 30cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.5 N.

Q64. F between 1μC and 6μC at 5cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=21.6 N.

Q65. F between 1μC and 6μC at 10cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=5.4 N.

Q66. F between 1μC and 6μC at 15cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=2.4 N.

Q67. F between 1μC and 6μC at 20cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=1.35 N.

Q68. F between 1μC and 6μC at 25cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.864 N.

Q69. F between 1μC and 6μC at 30cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.6 N.

Q70. F between 1μC and 7μC at 5cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=25.2 N.

Q71. F between 1μC and 7μC at 10cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=6.3 N.

Q72. F between 1μC and 7μC at 15cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=2.8 N.

Q73. F between 1μC and 7μC at 20cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=1.575 N.

Q74. F between 1μC and 7μC at 25cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=1.008 N.

Q75. F between 1μC and 7μC at 30cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.7 N.

Q76. F between 1μC and 8μC at 5cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=28.8 N.

Q77. F between 1μC and 8μC at 10cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=7.2 N.

Q78. F between 1μC and 8μC at 15cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=3.2 N.

Q79. F between 1μC and 8μC at 20cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=1.8 N.

Q80. F between 1μC and 8μC at 25cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=1.152 N.

Q81. F between 1μC and 8μC at 30cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.8 N.

Q82. F between 1μC and 9μC at 5cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=32.4 N.

Q83. F between 1μC and 9μC at 10cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=8.1 N.

Q84. F between 1μC and 9μC at 15cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=3.6 N.

Q85. F between 1μC and 9μC at 20cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=2.025 N.

Q86. F between 1μC and 9μC at 25cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=1.296 N.

Q87. F between 1μC and 9μC at 30cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.9 N.

Q88. F between 2μC and 1μC at 5cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=7.2 N.

Q89. F between 2μC and 1μC at 10cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=1.8 N.

Q90. F between 2μC and 1μC at 15cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.8 N.

Q91. F between 2μC and 1μC at 20cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.45 N.

Q92. F between 2μC and 1μC at 25cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.288 N.

Q93. F between 2μC and 1μC at 30cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.2 N.

Q94. F between 2μC and 2μC at 5cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=14.4 N.

Q95. F between 2μC and 2μC at 10cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=3.6 N.

Q96. F between 2μC and 2μC at 15cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=1.6 N.

Q97. F between 2μC and 2μC at 20cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.9 N.

Q98. F between 2μC and 2μC at 25cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.576 N.

Q99. F between 2μC and 2μC at 30cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=0.4 N.

Q100. F between 2μC and 3μC at 5cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=21.6 N.

Q101. F between 2μC and 3μC at 10cm:

Difficulty: Easy-Medium · Topic: Coulomb

Solution

F=kq1q2/r²=5.4 N.

Q102. Two point charges of +2μC and -2μC are placed 20 cm apart. The electric field at the midpoint is:

Difficulty: Medium · Topic: Electric Field

Solution

At midpoint both fields point in same direction (toward negative charge). E = 2 × kq/r² = 2 × 9×10⁹ × 2×10⁻⁶/0.01 = 3.6×10⁶. Total = 7.2×10⁶ N/C.

Q103. Electric flux through a closed surface enclosing charge q is:

Difficulty: Medium · Topic: Gauss's Law

Solution

By Gauss's law: q/ε₀.

Q104. Electric field inside a uniformly charged sphere at distance r from centre is:

Difficulty: Medium · Topic: Gauss's Law

Solution

By Gauss's law: (ρr)/(3ε₀).

Q105. Electric field due to infinite plane sheet of charge density σ is:

Difficulty: Medium · Topic: Gauss's Law

Solution

By Gauss's law: σ/(2ε₀).

Other Chapters in Physics

Ch 2: Electrostatic PotentialCh 3: Current ElectricityCh 4: Moving Charges & MagnetismCh 5: Magnetism & MatterCh 6: Electromagnetic InductionCh 7: Alternating CurrentCh 8: Electromagnetic WavesCh 9: Ray OpticsCh 10: Wave OpticsCh 11: Dual Nature of RadiationCh 12: AtomsCh 13: NucleiCh 14: Semiconductor Electronics

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