Chapter 3: Current Electricity

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

105

Questions

Topics

Solved Questions

Q1. In a Wheatstone bridge, the null condition is:

P/Q = R/S
P/R = Q/S
PR = QS
P+Q = R+S

Difficulty: Easy · Topic: Wheatstone Bridge

Solution

Wheatstone bridge is balanced when P/Q = R/S, and no current flows through the galvanometer.

Q2. Kirchhoff's junction rule is based on conservation of:

Energy
Charge
Momentum
Mass

Difficulty: Easy · Topic: Kirchhoff's Laws

Solution

Kirchhoff's current law (junction rule): ΣI = 0 at a junction, based on conservation of charge.

Q3. Five resistors of 10 Ω each are connected in parallel. The equivalent resistance is:

Difficulty: Easy · Topic: Parallel Resistance

Solution

R_eq = R/n = 10/5 = 2 Ω.

Q4. A current of 2 A flows through a conductor when 12 V is applied. The resistance is:

5 Ω
6 Ω
12 Ω
8 Ω

Difficulty: Easy · Topic: Ohm's Law

Solution

R = V/I = 12/2 = 6 Ω.

Q5. A current of 4 A flows through a conductor when 24 V is applied. The resistance is:

12 Ω
6 Ω
5 Ω
8 Ω

Difficulty: Easy · Topic: Ohm's Law

Solution

R = V/I = 24/4 = 6 Ω.

Q6. A current of 3 A flows through a conductor when 6 V is applied. The resistance is:

4 Ω
2 Ω
4 Ω
1 Ω

Difficulty: Easy · Topic: Ohm's Law

Solution

R = V/I = 6/3 = 2 Ω.

Q7. A current of 5 A flows through a conductor when 10 V is applied. The resistance is:

2 Ω
4 Ω
1 Ω
4 Ω

Difficulty: Easy · Topic: Ohm's Law

Solution

R = V/I = 10/5 = 2 Ω.

Q8. A current of 3 A flows through a conductor when 15 V is applied. The resistance is:

4 Ω
7 Ω
10 Ω
5 Ω

Difficulty: Easy · Topic: Ohm's Law

Solution

R = V/I = 15/3 = 5 Ω.

Q9. A current of 4 A flows through a conductor when 20 V is applied. The resistance is:

7 Ω
10 Ω
4 Ω
5 Ω

Difficulty: Easy · Topic: Ohm's Law

Solution

R = V/I = 20/4 = 5 Ω.

Q10. A current of 3 A flows through a conductor when 9 V is applied. The resistance is:

3 Ω
5 Ω
6 Ω
2 Ω

Difficulty: Easy · Topic: Ohm's Law

Solution

R = V/I = 9/3 = 3 Ω.

Q11. A current of 6 A flows through a conductor when 30 V is applied. The resistance is:

10 Ω
5 Ω
4 Ω
7 Ω

Difficulty: Easy · Topic: Ohm's Law

Solution

R = V/I = 30/6 = 5 Ω.

Q12. A current of 2 A flows through a conductor when 8 V is applied. The resistance is:

4 Ω
6 Ω
8 Ω
3 Ω

Difficulty: Easy · Topic: Ohm's Law

Solution

R = V/I = 8/2 = 4 Ω.

Q13. A current of 10 A flows through a conductor when 100 V is applied. The resistance is:

10 Ω
12 Ω
20 Ω
9 Ω

Difficulty: Easy · Topic: Ohm's Law

Solution

R = V/I = 100/10 = 10 Ω.

Q14. Resistors 2Ω, 3Ω, 6Ω in series give total resistance:

Difficulty: Easy · Topic: Series Resistance

Solution

R = 2+3+6 = 11 Ω.

Q15. Resistors 4Ω, 4Ω, 4Ω in series give total resistance:

Difficulty: Easy · Topic: Series Resistance

Solution

R = 4+4+4 = 12 Ω.

Q16. Resistors 1Ω, 2Ω, 3Ω in series give total resistance:

Difficulty: Easy · Topic: Series Resistance

Solution

R = 1+2+3 = 6 Ω.

Q17. Resistors 5Ω, 10Ω, 10Ω in series give total resistance:

Difficulty: Easy · Topic: Series Resistance

Solution

R = 5+10+10 = 25 Ω.

Q18. Resistors 3Ω, 6Ω, 9Ω in series give total resistance:

Difficulty: Easy · Topic: Series Resistance

Solution

R = 3+6+9 = 18 Ω.

Q19. V=1V, I=1A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=1.0 Ω.

Q20. V=1V, I=2A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.5 Ω.

Q21. V=1V, I=3A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.33 Ω.

Q22. V=1V, I=4A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.25 Ω.

Q23. V=1V, I=5A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.2 Ω.

Q24. V=1V, I=6A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.17 Ω.

Q25. V=1V, I=7A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.14 Ω.

Q26. V=1V, I=8A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.12 Ω.

Q27. V=1V, I=9A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.11 Ω.

Q28. V=1V, I=10A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.1 Ω.

Q29. V=1V, I=11A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.09 Ω.

Q30. V=1V, I=12A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.08 Ω.

Q31. V=1V, I=13A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.08 Ω.

Q32. V=1V, I=14A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.07 Ω.

Q33. V=1V, I=15A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.07 Ω.

Q34. V=1V, I=16A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.06 Ω.

Q35. V=1V, I=17A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.06 Ω.

Q36. V=1V, I=18A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.06 Ω.

Q37. V=1V, I=19A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.05 Ω.

Q38. V=2V, I=1A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=2.0 Ω.

Q39. V=2V, I=2A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=1.0 Ω.

Q40. V=2V, I=3A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.67 Ω.

Q41. V=2V, I=4A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.5 Ω.

Q42. V=2V, I=5A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.4 Ω.

Q43. V=2V, I=6A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.33 Ω.

Q44. V=2V, I=7A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.29 Ω.

Q45. V=2V, I=8A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.25 Ω.

Q46. V=2V, I=9A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.22 Ω.

Q47. V=2V, I=10A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.2 Ω.

Q48. V=2V, I=11A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.18 Ω.

Q49. V=2V, I=12A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.17 Ω.

Q50. V=2V, I=13A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.15 Ω.

Q51. V=2V, I=14A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.14 Ω.

Q52. V=2V, I=15A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.13 Ω.

Q53. V=2V, I=16A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.12 Ω.

Q54. V=2V, I=17A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.12 Ω.

Q55. V=2V, I=18A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.11 Ω.

Q56. V=2V, I=19A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.11 Ω.

Q57. V=3V, I=1A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=3.0 Ω.

Q58. V=3V, I=2A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=1.5 Ω.

Q59. V=3V, I=3A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=1.0 Ω.

Q60. V=3V, I=4A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.75 Ω.

Q61. V=3V, I=5A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.6 Ω.

Q62. V=3V, I=6A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.5 Ω.

Q63. V=3V, I=7A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.43 Ω.

Q64. V=3V, I=8A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.38 Ω.

Q65. V=3V, I=9A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.33 Ω.

Q66. V=3V, I=10A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.3 Ω.

Q67. V=3V, I=11A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.27 Ω.

Q68. V=3V, I=12A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.25 Ω.

Q69. V=3V, I=13A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.23 Ω.

Q70. V=3V, I=14A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.21 Ω.

Q71. V=3V, I=15A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.2 Ω.

Q72. V=3V, I=16A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.19 Ω.

Q73. V=3V, I=17A. Resistance:

Difficulty: Easy · Topic: Ohm's Law

Solution

R=V/I=0.18 Ω.

Q74. The resistance of a wire is doubled when its length is doubled and area is halved. The resistivity:

Doubles
Halves
Remains same
Quadruples

Difficulty: Easy-Medium · Topic: Resistivity

Solution

R = ρL/A. If L→2L, A→A/2: R' = ρ(2L)/(A/2) = 4ρL/A = 4R. Resistivity ρ is a material property and does not change.

Q75. The internal resistance of a cell can be determined using:

Ohm's law only
Potentiometer
Ammeter only
Voltmeter only

Difficulty: Easy-Medium · Topic: Internal Resistance

Solution

A potentiometer can accurately measure the internal resistance by comparing EMF with terminal voltage.

Q76. Resistors 2Ω, 3Ω, 6Ω in parallel give equivalent resistance:

Difficulty: Easy-Medium · Topic: Parallel Resistance

Solution

1/R = 1/2+1/3+1/6. R = 1.0 Ω.

Q77. Resistors 4Ω, 4Ω, 4Ω in parallel give equivalent resistance:

Difficulty: Easy-Medium · Topic: Parallel Resistance

Solution

1/R = 1/4+1/4+1/4. R = 1.33 Ω.

Q78. Resistors 1Ω, 2Ω, 3Ω in parallel give equivalent resistance:

Difficulty: Easy-Medium · Topic: Parallel Resistance

Solution

1/R = 1/1+1/2+1/3. R = 0.55 Ω.

Q79. Resistors 5Ω, 10Ω, 10Ω in parallel give equivalent resistance:

Difficulty: Easy-Medium · Topic: Parallel Resistance

Solution

1/R = 1/5+1/10+1/10. R = 2.5 Ω.

Q80. Resistors 3Ω, 6Ω, 9Ω in parallel give equivalent resistance:

Difficulty: Easy-Medium · Topic: Parallel Resistance

Solution

1/R = 1/3+1/6+1/9. R = 1.64 Ω.

Q81. Power dissipated in a 3Ω resistor with 12V across it is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = V²/R = 12²/3 = 48 W.

Q82. Power dissipated in a 6Ω resistor with 24V across it is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = V²/R = 24²/6 = 96 W.

Q83. Power dissipated in a 2Ω resistor with 10V across it is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = V²/R = 10²/2 = 50 W.

Q84. Power dissipated in a 5Ω resistor with 20V across it is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = V²/R = 20²/5 = 80 W.

Q85. Power dissipated in a 2Ω resistor with 6V across it is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = V²/R = 6²/2 = 18 W.

Q86. Power dissipated when 2 A flows through 5 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q87. Power dissipated when 3 A flows through 7 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q88. Power dissipated when 4 A flows through 9 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q89. Power dissipated when 5 A flows through 11 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q90. Power dissipated when 6 A flows through 13 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q91. Power dissipated when 7 A flows through 15 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q92. Power dissipated when 8 A flows through 17 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q93. Power dissipated when 9 A flows through 19 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q94. Power dissipated when 10 A flows through 21 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q95. Power dissipated when 11 A flows through 23 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q96. Power dissipated when 12 A flows through 25 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q97. Power dissipated when 13 A flows through 27 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q98. Power dissipated when 14 A flows through 29 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q99. Power dissipated when 15 A flows through 31 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q100. Power dissipated when 16 A flows through 33 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q101. Power dissipated when 17 A flows through 35 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q102. Power dissipated when 18 A flows through 37 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q103. Power dissipated when 19 A flows through 39 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q104. Power dissipated when 20 A flows through 41 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Q105. Power dissipated when 21 A flows through 43 Ω is:

Difficulty: Easy-Medium · Topic: Power

Solution

P = I²R.

Other Chapters in Physics

Ch 1: Electric Charges & Fields Ch 2: Electrostatic Potential Ch 4: Moving Charges & Magnetism Ch 5: Magnetism & Matter Ch 6: Electromagnetic Induction Ch 7: Alternating Current Ch 8: Electromagnetic Waves Ch 9: Ray Optics Ch 10: Wave Optics Ch 11: Dual Nature of Radiation Ch 12: Atoms Ch 13: Nuclei Ch 14: Semiconductor Electronics

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