Electricity Part 1: MCQs (Q1–Q25)
⚡ Electricity – MCQs (Class 10 Science, NCERT)
🔹 Part 1: Questions 1–25
Q1. The SI unit of electric current is:
A) Volt
B) Ampere
C) Ohm
D) Coulomb
Correct Answer: B) Ampere
Explanation:
- A) Volt → Unit of potential difference.
- ✅ B) Ampere → 1 A = 1 C/s.
- C) Ohm → Unit of resistance.
- D) Coulomb → Unit of charge.
Q2. Electric current is the flow of:
A) Protons
B) Neutrons
C) Electrons
D) Atoms
Correct Answer: C) Electrons
Explanation:
- A, B, D → Do not flow in conductors.
- ✅ C) Current in metals is due to flow of electrons.
Q3. The potential difference between two points is 1 volt if:
A) 1 joule of work is done in moving 1 coulomb charge
B) 1 coulomb of charge passes per second
C) 1 watt of power is consumed
D) Resistance is 1 ohm
Correct Answer: A) 1 joule of work is done in moving 1 coulomb charge
Explanation:
- ✅ A) V = W/Q.
- B) Current definition.
- C) Power relation.
- D) Ohm’s law, not definition.
Q4. Ohm’s law states that:
A) V ∝ I when T constant
B) V ∝ 1/I
C) I ∝ R
D) V independent of I
Correct Answer: A) V ∝ I when T constant
Explanation:
- ✅ A) Ohm’s law: V = IR.
- B, C, D → Incorrect statements.
Q5. Resistance depends on:
A) Length of conductor
B) Area of cross-section
C) Material
D) All of these
Correct Answer: D) All of these
Explanation:
- ✅ D) R = ρL/A → depends on length, area, and material resistivity.
Q6. The SI unit of resistance is:
A) Ohm
B) Ampere
C) Volt
D) Watt
Correct Answer: A) Ohm
Explanation:
- ✅ A) Ohm (Ω) = V/A.
- B, C, D → Other electrical units.
Q7. The resistivity of a conductor depends on:
A) Length
B) Area
C) Temperature and material
D) Current
Correct Answer: C) Temperature and material
Explanation:
- ✅ C) Resistivity is a property of material and temperature.
- A, B → Affect resistance, not resistivity.
- D → Not direct.
Q8. If length of a conductor is doubled, its resistance will:
A) Become half
B) Become double
C) Remain same
D) Become four times
Correct Answer: B) Become double
Explanation:
- ✅ B) R ∝ L. Doubling L doubles R.
Q9. If area of cross-section of wire is doubled, resistance will:
A) Remain same
B) Double
C) Become half
D) Become four times
Correct Answer: C) Become half
Explanation:
- ✅ C) R ∝ 1/A.
Q10. The SI unit of electric power is:
A) Joule
B) Watt
C) Newton
D) Ampere
Correct Answer: B) Watt
Explanation:
- ✅ B) P = VI, unit watt.
- A, C, D → Units of other quantities.
Q11. One kilowatt-hour is equal to:
A) 1000 J
B) 3600 J
C) 36 × 10⁵ J
D) 3.6 × 10⁶ J
Correct Answer: D) 3.6 × 10⁶ J
Explanation:
- ✅ D) 1 kWh = 1000 W × 3600 s = 3.6 × 10⁶ J.
Q12. The device used to measure current is:
A) Voltmeter
B) Ammeter
C) Galvanometer
D) Potentiometer
Correct Answer: B) Ammeter
Explanation:
- ✅ B) Ammeter → Connected in series.
- A) Voltmeter → Measures voltage.
- C, D → Not current measuring devices directly.
Q13. Voltmeter is always connected in:
A) Series with circuit
B) Parallel across component
C) Parallel with battery
D) Series with resistor
Correct Answer: B) Parallel across component
Explanation:
- ✅ B) Voltmeter → Measures potential difference across component.
Q14. The resistance of a conductor is 10 Ω. If current 2 A flows, potential difference is:
A) 5 V
B) 10 V
C) 15 V
D) 20 V
Correct Answer: D) 20 V
Explanation:
- V = IR = 2 × 10 = 20 V. ✅ D correct.
Q15. The commercial unit of electric energy is:
A) Joule
B) Kilowatt-hour
C) Watt
D) Ampere-hour
Correct Answer: B) Kilowatt-hour
Explanation:
- ✅ B) kWh is used for billing.
- A) Joule is SI unit but impractical.
- C, D → Not correct.
Q16. In a series circuit, current is:
A) Same in all components
B) Different in each component
C) Zero
D) Infinite
Correct Answer: A) Same in all components
Explanation:
- ✅ A) Series → Only one path for current.
Q17. In a parallel circuit, potential difference is:
A) Same across each branch
B) Different in each branch
C) Zero
D) Half of supply
Correct Answer: A) Same across each branch
Explanation:
- ✅ A) Parallel → All branches directly across supply.
Q18. Three resistors of 2 Ω, 3 Ω, 6 Ω in series. Equivalent resistance is:
A) 1 Ω
B) 2 Ω
C) 6 Ω
D) 11 Ω
Correct Answer: D) 11 Ω
Explanation:
- Series → R = 2+3+6 = 11 Ω. ✅
Q19. Three resistors of 2 Ω, 3 Ω, 6 Ω in parallel. Equivalent resistance is:
A) 1 Ω
B) 2 Ω
C) 3 Ω
D) 6 Ω
Correct Answer: A) 1 Ω
Explanation:
- 1/R = 1/2 + 1/3 + 1/6 = 1 → R = 1 Ω. ✅
Q20. The heating effect of current is expressed by:
A) P = VI
B) H = I²Rt
C) V = IR
D) Q = It
Correct Answer: B) H = I²Rt
Explanation:
- ✅ B) Joule’s law of heating.
Q21. Electric fuse works on principle of:
A) Chemical effect of current
B) Magnetic effect of current
C) Heating effect of current
D) Induction
Correct Answer: C) Heating effect of current
Explanation:
- ✅ C) Fuse wire melts due to excessive heating.
Q22. The resistance of a conductor increases with:
A) Decrease in length
B) Increase in length
C) Increase in area
D) Cooling
Correct Answer: B) Increase in length
Explanation:
- ✅ B) R ∝ L.
Q23. When two resistors R1 and R2 are in parallel, their equivalent resistance is:
A) Greater than both
B) Less than both
C) Average of both
D) Product of both
Correct Answer: B) Less than both
Explanation:
- ✅ B) Parallel resistance always smaller than smallest resistor.
Q24. A 60 W bulb glows brighter than a 40 W bulb because:
A) It has more resistance
B) It has less resistance
C) It consumes less energy
D) It is bigger
Correct Answer: B) It has less resistance
Explanation:
- ✅ B) Power ∝ V²/R → Lower resistance → Higher power.
Q25. Which quantity remains constant in series combination of resistors?
A) Voltage
B) Current
C) Resistance
D) Power
Correct Answer: B) Current
Explanation:
- ✅ B) In series → Same current flows through each resistor.
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