Electricity — Class 10 MCQs with Answers

Electricity — important questions & MCQs with answers (Class 10 Science (Physics))

14 solved questions from this chapter's difficulty levels, each with its answer and explanation. The other 76 are timed and scored when you sign in.

1. Q1Easy

   The SI unit of electric current is:

   A.Volt

   B.Ampere✓ Correct

   C.Ohm

   D.Coulomb

   Answer: B. Ampere

   Explanation: Current is the rate of flow of charge, I = Q/t, so its SI unit is the ampere (1 A = 1 C/s); coulomb measures the charge itself, not its rate of flow, so it isn't the current unit.

2. Q2Easy

   Electric power dissipated in a resistor is:

   A.P = V·I✓ Correct

   B.P = V/I

   C.P = I²/R

   D.P = R/I

   Answer: A. P = V·I

   Explanation: Power dissipated equals P = V × I, which can also be written as I²R or V²/R using Ohm's law; V/I instead gives resistance, and I²/R isn't a valid power expression.

3. Q3Easy

   Electric current is the:

   A.Power

   B.Voltage

   C.Rate of flow of charge✓ Correct

   D.Energy

   Answer: C. Rate of flow of charge

   Explanation: Electric current I is defined as the rate of flow of charge, I = Q/t, measured in amperes; it is not itself a form of energy or power, which are separate quantities.

4. Q4Easy

   Potential difference is:

   A.Charge per unit time

   B.Work done per unit charge✓ Correct

   C.Resistance × current

   D.Force per charge

   Answer: B. Work done per unit charge

   Explanation: By definition, potential difference is the work done per unit charge moved between two points, V = W/Q, measured in volts; V = IR is a consequence of Ohm's law, not the basic definition.

5. Q5Easy

   Resistance is the property of a conductor that:

   A.Opposes flow of current✓ Correct

   B.Conducts current

   C.Stores charge

   D.Generates voltage

   Answer: A. Opposes flow of current

   Explanation: Resistance is the property of a conductor that opposes the flow of current through it, measured in ohms as R = V/I; it doesn't conduct, store charge, or generate voltage on its own.

6. Q6Easy

   R = ρL/A where ρ is:

   A.Current density

   B.Conductance

   C.Power

   D.Resistivity✓ Correct

   Answer: D. Resistivity

   Explanation: In R = ρL/A, ρ is resistivity — a property of the material itself, independent of the wire's shape or size, unlike R which depends on length and area too.

7. Q7Medium

   A 220 V appliance draws 2 A. Its resistance is:

   A.110 Ω✓ Correct

   B.55 Ω

   C.440 Ω

   D.220 Ω

   Answer: A. 110 Ω

   Explanation: Ohm's law gives R = V/I = 220 ÷ 2 = 110 Ω; multiplying V × I instead of dividing would wrongly give 440 Ω.

8. Q8Medium

   A bulb is marked 100 W, 220 V. Resistance of filament:

   A.2200 Ω

   B.100 Ω

   C.220 Ω

   D.484 Ω✓ Correct

   Answer: D. 484 Ω

   Explanation: Using P = V²/R, the filament's resistance is R = V²/P = 220² ÷ 100 = 48400 ÷ 100 = 484 Ω; computing V/P instead of V²/P gives a far smaller, incorrect value.

9. Q9Medium

   R = ρL/A. If L doubles and A is halved, new resistance is:

   A.R/4

   B.R

   C.2 R

   D.4 R✓ Correct

   Answer: D. 4 R

   Explanation: Since R = ρL/A, doubling length to 2L and halving area to A/2 multiplies R by 4, giving 4R; considering only the length change would wrongly suggest just 2R.

10. Q10Medium

    Lowest resistivity at room temperature is for:

    A.Silver✓ Correct

    B.Copper

    C.Aluminium

    D.Iron

    Answer: A. Silver

    Explanation: Silver has the lowest electrical resistivity of common metals, making it an even better conductor than copper — though copper is preferred commercially since it's far cheaper for the same job.

11. Q11Medium

    Three resistors 2 Ω, 3 Ω, 5 Ω are connected in series. Total resistance:

    A.0.97 Ω

    B.30 Ω

    C.10 Ω✓ Correct

    D.1 Ω

    Answer: C. 10 Ω

    Explanation: Series resistances simply add: R = R₁ + R₂ + R₃ = 2 + 3 + 5 = 10 Ω; applying the parallel reciprocal formula instead would wrongly give about 0.97 Ω here.

12. Q12Hard

    V-I graph for an ohmic conductor is:

    A.Horizontal line

    B.A curve

    C.A straight line through origin✓ Correct

    D.Vertical line

    Answer: C. A straight line through origin

    Explanation: An ohmic conductor obeys V = IR, so V ∝ I and its V–I graph is a straight line through the origin.

13. Q13Hard

    A 1500 W heater runs for 2 hours. Energy consumed (in kWh) is:

    A.1.5

    B.3✓ Correct

    C.30

    D.300

    Answer: B. 3

    Explanation: Energy E = P × t = 1.5 kW × 2 h = 3 kWh; forgetting to convert 1500 W to 1.5 kW would wrongly give 3000 kWh.

14. Q14Hard

    A wire of resistance R is stretched to twice its length without changing its volume. New resistance:

    A.2 R

    B.4 R✓ Correct

    C.R

    D.R/2

    Answer: B. 4 R

    Explanation: Volume stays constant, so doubling length to 2L halves the area to A/2; since R = ρL/A, the new resistance is ρ(2L)/(A/2) = 4 × ρL/A = 4R.

Electricity — FAQs

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