CBSE Class 10 - Electricity Notes & MCQ

Electricity

1. Electric Current

Electric current is the flow of electric charge through a conductor.

Formula: I = Q / t

• I = Current (Ampere)
• Q = Charge (Coulomb)
• t = Time (second)

1 Ampere is the flow of 1 Coulomb of charge per second.

2. Electric Potential Difference

It is the work done to move a unit charge from one point to another.

Formula: V = W / Q

1 Volt = 1 Joule work done per Coulomb charge.

3. Electric Circuit

An electric circuit is a closed conducting path through which electric current flows.

• Cell
• Battery
• Switch
• Resistor
• Ammeter
• Voltmeter

4. Ohm’s Law

At constant temperature, current through a conductor is directly proportional to the potential difference.

V = IR

The V–I graph is a straight line passing through the origin.

5. Resistance

Resistance is the opposition offered by a conductor to the flow of electric current.

Formula: R = ρL / A

• Length of conductor
• Area of cross-section
• Nature of material
• Temperature

6. Resistors in Series

In series combination, the same current flows through all resistors.

R = R₁ + R₂ + R₃

Used in electric heaters.

7. Resistors in Parallel

In parallel combination, the same voltage is applied across each resistor.

1/R = 1/R₁ + 1/R₂ + 1/R₃

Used in household wiring.

8. Electric Power

Electric power is the rate at which electrical energy is consumed.

P = VI
P = I²R
P = V² / R

Unit: Watt (W)

9. Electrical Energy

Electrical energy consumed by an appliance.

E = P × t

1 unit = 1 kWh = 3.6 × 10⁶ Joule

10. Heating Effect of Electric Current

When electric current flows through a resistor, heat is produced.

H = I²Rt

• Electric iron
• Heater
• Electric fuse

11. Electric Fuse

An electric fuse is a safety device made of thin wire with low melting point.

It protects appliances from overloading and short circuit.

Important Formula Table

Quantity	Formula
Current	I = Q / t
Voltage	V = W / Q
Ohm’s Law	V = IR
Resistance	R = ρL / A
Power	P = VI
Energy	E = Pt
Heating Effect	H = I²Rt

Important Exam Points

• Ammeter is connected in series
• Voltmeter is connected in parallel
• Household wiring uses parallel combination
• Thicker wire has less resistance

CBSE Class 10 Science – Electricity MCQs

1. The SI unit of electric current is:

a) Volt
b) Ohm
c) Ampere
d) Watt

Answer: c) Ampere

2. Electric current is the flow of:

a) Energy
b) Electrons
c) Charges
d) Protons

Answer: c) Charges

3. The instrument used to measure electric current is:

a) Voltmeter
b) Ammeter
c) Galvanometer
d) Ohmmeter

Answer: b) Ammeter

4. Potential difference is measured in:

a) Ampere
b) Ohm
c) Volt
d) Watt

Answer: c) Volt

5. Ohm’s Law is represented by:

a) V = I/R
b) V = IR
c) I = VR
d) R = VI

Answer: b) V = IR

6. The SI unit of resistance is:

a) Volt
b) Ampere
c) Ohm
d) Joule

Answer: c) Ohm

7. Resistance of a conductor depends on:

a) Length
b) Area of cross-section
c) Material
d) All of these

Answer: d) All of these

8. The V–I graph for a metallic conductor is:

a) Curved
b) Horizontal line
c) Vertical line
d) Straight line

Answer: d) Straight line

9. In a series circuit, the current is:

a) Different in each resistor
b) Same in all resistors
c) Zero
d) Maximum

Answer: b) Same in all resistors

10. In parallel combination of resistors:

a) Same current flows
b) Same voltage is applied
c) Resistance increases
d) Circuit breaks

Answer: b) Same voltage is applied

11. Household wiring is done using:

a) Series circuit
b) Parallel circuit
c) Mixed circuit
d) Open circuit

Answer: b) Parallel circuit

12. Electric power is measured in:

a) Joule
b) Volt
c) Watt
d) Ampere

Answer: c) Watt

13. Electric power is given by:

a) P = IR
b) P = VI
c) P = V/I
d) P = R/I

Answer: b) P = VI

14. Commercial unit of electrical energy is:

a) Joule
b) Watt
c) kWh
d) Ampere

Answer: c) kWh

15. 1 kWh is equal to:

a) 3.6 × 10⁵ J
b) 3.6 × 10⁶ J
c) 3.6 × 10⁷ J
d) 36 × 10⁶ J

Answer: b) 3.6 × 10⁶ J

16. Heating effect of electric current is given by:

a) H = IRt
b) H = I²Rt
c) H = VIt
d) H = RIt

Answer: b) H = I²Rt

17. Which device works on heating effect of current?

a) Electric bell
b) Generator
c) Electric iron
d) Motor

Answer: c) Electric iron

18. An electric fuse is used to:

a) Increase current
b) Reduce voltage
c) Measure power
d) Protect appliances

Answer: d) Protect appliances

19. A fuse wire has:

a) High melting point
b) Low melting point
c) High resistance only
d) Zero resistance

Answer: b) Low melting point

20. Thicker wires have:

a) More resistance
b) Less resistance
c) Same resistance
d) Infinite resistance

Answer: b) Less resistance