Electricity Part 3: MCQs (Q51–Q75)
⚡ Electricity – MCQs (Class 10 Science, NCERT)
🔹 Part 3: Questions 51–75
Q51. A current of 0.5 A flows through a conductor for 10 minutes. The charge passed is:
A) 50 C
B) 100 C
C) 300 C
D) 600 C
Correct Answer: D) 600 C
Explanation:
- Q = I × t = 0.5 × (10 × 60) = 0.5 × 600 = 300 C.
- Oops correction → actual = 300 C, so answer is C. ✅
- A, B, D → Miscalculated values.
Q52. A wire of resistance R is cut into 3 equal parts and joined in parallel. Equivalent resistance is:
A) R
B) R/3
C) R/6
D) R/9
Correct Answer: D) R/9
Explanation:
- Each part = R/3.
- In parallel: 1/R_eq = 3/(R/3) = 9/R → R_eq = R/9. ✅
Q53. Which physical quantity is measured in kilowatt-hour?
A) Energy
B) Power
C) Resistance
D) Current
Correct Answer: A) Energy
Explanation:
- ✅ A) kWh = unit of electrical energy.
- B = Power (kW), C = Ω, D = A.
Q54. A 100 W bulb is used for 10 hours. Energy consumed is:
A) 1 kWh
B) 10 kWh
C) 100 kWh
D) 0.1 kWh
Correct Answer: A) 1 kWh
Explanation:
- E = P × t = 100/1000 × 10 = 1 kWh. ✅
Q55. The SI unit of electric field is:
A) V
B) V/m
C) N
D) Ω
Correct Answer: B) V/m
Explanation:
- ✅ B) Electric field = Force/charge = V/m.
Q56. The heating effect of current is directly proportional to:
A) Square of current
B) Resistance
C) Time
D) All of these
Correct Answer: D) All of these
Explanation:
- H = I²Rt → ∝ I², R, t. ✅
Q57. The resistance of an electric bulb filament is:
A) Zero
B) Low
C) High
D) Infinite
Correct Answer: C) High
Explanation:
- ✅ C) High resistance → Produces heat & light.
Q58. In a circuit, 5 A current flows through 2 Ω resistor. Power dissipated is:
A) 10 W
B) 20 W
C) 25 W
D) 50 W
Correct Answer: D) 50 W
Explanation:
- P = I²R = 25 × 2 = 50 W. ✅
Q59. In series combination of resistors:
A) Current same, voltage divides
B) Voltage same, current divides
C) Both current & voltage same
D) Resistance decreases
Correct Answer: A) Current same, voltage divides
Explanation:
- ✅ A) Current constant, V distributes.
Q60. In parallel combination of resistors:
A) Current same, voltage divides
B) Voltage same, current divides
C) Both current & voltage same
D) Resistance increases
Correct Answer: B) Voltage same, current divides
Explanation:
- ✅ B) Parallel → Voltage constant, current splits.
Q61. Which material is used for making heating elements?
A) Copper
B) Aluminium
C) Tungsten
D) Nichrome
Correct Answer: D) Nichrome
Explanation:
- ✅ D) Nichrome → High resistivity & melting point.
Q62. Which law is used to calculate equivalent resistance in series/parallel?
A) Coulomb’s law
B) Ohm’s law
C) Newton’s law
D) Joule’s law
Correct Answer: B) Ohm’s law
Explanation:
- ✅ B) V = IR forms basis of circuit analysis.
Q63. A 60 W bulb consumes 240 J energy in:
A) 1 s
B) 2 s
C) 3 s
D) 4 s
Correct Answer: A) 1 s
Explanation:
- P = E/t → t = E/P = 240/60 = 4 s. ✅ Correct answer is D.
Q64. Resistivity of a material depends on:
A) Length
B) Cross-section
C) Nature and temperature
D) Shape
Correct Answer: C) Nature and temperature
Explanation:
- ✅ C) Resistivity is material property.
Q65. In domestic electric circuit, fuse is connected in:
A) Neutral wire
B) Earth wire
C) Live wire
D) Both live & neutral
Correct Answer: C) Live wire
Explanation:
- ✅ C) Fuse breaks supply instantly in case of excess current.
Q66. Electric power consumed in circuit is zero when:
A) Current is zero
B) Voltage is zero
C) Resistance infinite
D) All of these
Correct Answer: D) All of these
Explanation:
- P = VI → Zero if any factor is zero. ✅
Q67. For the same current, heat produced in two resistors is proportional to:
A) R
B) 1/R
C) R²
D) √R
Correct Answer: A) R
Explanation:
- H = I²Rt → ∝ R. ✅
Q68. A conductor offers least resistance when:
A) Short & thick
B) Long & thin
C) Long & thick
D) Short & thin
Correct Answer: A) Short & thick
Explanation:
- R = ρL/A → Min for small L, large A. ✅
Q69. Which factor does NOT affect resistance of a wire?
A) Length
B) Temperature
C) Cross-section area
D) Voltage applied
Correct Answer: D) Voltage applied
Explanation:
- ✅ D) R = ρL/A independent of voltage.
Q70. A 60 W and 100 W bulb are connected in series. Which glows brighter?
A) 60 W
B) 100 W
C) Both equal
D) None
Correct Answer: A) 60 W
Explanation:
- In series, same current flows. Brighter = higher R. R = V²/P → 60 W > 100 W. ✅
Q71. Which device measures electric energy directly?
A) Voltmeter
B) Ammeter
C) Wattmeter
D) Energy meter
Correct Answer: D) Energy meter
Explanation:
- ✅ D) Energy meter (kWh meter) in homes.
Q72. A 10 Ω resistor carries 2 A current for 5 s. Work done is:
A) 100 J
B) 200 J
C) 250 J
D) 400 J
Correct Answer: D) 200 J
Explanation:
- W = I²Rt = 4 × 10 × 5 = 200 J. ✅
Q73. Resistance of alloy manganin is:
A) Very high
B) Very low
C) Almost independent of temperature
D) Zero
Correct Answer: C) Almost independent of temperature
Explanation:
- ✅ C) Manganin → Used for standard resistors.
Q74. A device used to protect electrical appliances from short-circuit is:
A) Transformer
B) Fuse
C) Capacitor
D) Inductor
Correct Answer: B) Fuse
Explanation:
- ✅ B) Fuse wire melts, breaks current.
Q75. Which of the following is NOT a consequence of heating effect of current?
A) Electric bulb
B) Electric heater
C) Electric fuse
D) Electric motor
Correct Answer: D) Electric motor
Explanation:
- ✅ D) Motor works on magnetic effect, not heating.
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