⚡ Class 10 Science — Electricity Original Visual Revision Notes
Aligned with the Class 10 Science syllabus. Independently created study material. Not affiliated with or endorsed by NCERT.
Real-world connection: Think of electricity like water flowing through pipes. Voltage (V) is the water pressure pushing the water forward. Current (I) is the rate of water flow. Resistance (R) is like a narrow section of the pipe that slows the flow. A higher pressure or a wider pipe means more water — just as higher voltage or lower resistance gives more current.
⚡ Topic 1: Electric Current
Current is the flow of electric charge.
Charges move through a wire.
We measure current in ampere (A).
An ammeter measures the current flow.
Current flows from positive to negative.
🔋 Topic 2: Electric Circuit
A circuit is a closed path for current.
It needs a battery to push charges.
A switch can open or close the path.
Wires connect all parts together.
No gap means it is a closed circuit.
🔌 Topic 3: Electric Potential (Voltage)
Voltage is the push given to charges.
We measure voltage in volts (V).
A voltmeter measures the voltage.
Battery gives energy to the charges.
Higher voltage means stronger push.
📏 Topic 4: Ohm's Law (V = IR)
Ohm's law says V equals I times R.
V is voltage in volts.
I is current in ampere.
R is resistance in ohm.
More voltage gives more current.
🛡 Topic 5: Resistance
Resistance slows down the current flow.
We measure it in ohm.
Thin wire has more resistance.
Long wire has more resistance too.
Some metals have low resistance.
🔗 Topic 6: Factors Affecting Resistance
Length: longer wire means more resistance.
Thickness: thinner wire means more resistance.
Material: copper has very low resistance.
Temperature: hot wire has more resistance.
R depends on length, area, and material.
🔄 Topic 7: Resistors in Series
In series, resistors are in one line.
Same current flows through all of them.
Total R = R1 + R2 + R3.
Total resistance goes up in series.
If one breaks, all stop working.
🔀 Topic 8: Resistors in Parallel
In parallel, resistors have separate paths.
Same voltage is across each resistor.
Total R is less than the smallest one.
1/R = 1/R1 + 1/R2 + 1/R3.
If one breaks, others still work.
🔥 Topic 9: Heating Effect of Current
Current makes wire hot due to resistance.
Heat produced = I² × R × t.
Heater and iron use this heating effect.
Filament in bulb glows when very hot.
More resistance gives more heat.
💡 Topic 10: Electric Power and Energy
Power is how fast energy is used.
P = V × I (voltage times current).
We measure power in watt (W).
Electric energy = P × t (power times time).
We pay for energy in kilowatt-hour (kWh).
🎨 Section 2 — Easy Illustrations
Diagram 1: A simple electric circuit with battery, switch, and bulb
Diagram 2: The Ohm's Law triangle helps find V, I, or R
Diagram 3: Series has one path; parallel has many paths
Diagram 4: Heating effect is used in heaters, bulbs, and irons
Diagram 5: Power, energy, bills, and safety devices
✏️ Section 3 — Worked Examples
📝 Example 1: Find the Current (Ohm's Law)
A bulb has 12 V and 4 Ω resistance. Find I.
1
Write the formula: V = I × R.
2
Put the values: 12 = I × 4.
3
Divide both sides by 4.
4
I = 12 ÷ 4 = 3.
Answer: The current is 3 ampere (A).
📝 Example 2: Series Resistance
Three resistors: 2 Ω, 3 Ω, 5 Ω in series. Find total.
1
In series, add all the resistances.
2
R total = 2 + 3 + 5.
3
R total = 10 ohm.
Answer: Total resistance is 10 Ω.
📝 Example 3: Find Electric Power
A heater uses 5 A at 220 V. Find power.
1
Write the formula: P = V × I.
2
Put the values: P = 220 × 5.
3
P = 1100 watt.
4
1100 W = 1.1 kilowatt (kW).
Answer: The power is 1100 W or 1.1 kW.
📋 Section 4 — Cheat Sheet
Word
Meaning
Current
Flow of electric charge through a wire.
Voltage
The push that moves the charges forward.
Resistance
It slows down the flow of current.
Ohm's Law
V = I times R links three things.
Ammeter
Tool to measure current in ampere.
Voltmeter
Tool to measure voltage in volts.
Series
Resistors connected in one single line.
Parallel
Resistors connected in separate paths.
Power
How fast energy is used (P = VI).
Kilowatt-hour
Unit to measure energy for billing.
Fuse
Safety wire that melts if current is high.
MCB
Switch that trips off on high current.
🏠 Section 5 — Take-Home Handout
Part A: Fill in the Blanks
1. Flow of charge is called electric ________.
2. We measure current using an ________.
3. V = I × R is called ________ law.
4. Power is measured in ________.
5. A ________ melts when current is too high.
Part B: True or False
1. Current is measured in volts. ________
2. Thicker wire has less resistance. ________
3. In series, total R goes down. ________
4. P = V times I gives power. ________
5. MCB is a safety device. ________
Part C: Solve
1. V = 6 V, R = 2 Ω. Find the current (I).
2. A fan uses 2 A at 220 V. Find the power.
Part D: Match the Columns
Column A
Column B
1. Ammeter
a. Measures voltage
2. Voltmeter
b. Measures current
3. Fuse
c. V = I × R
4. Ohm's Law
d. Safety device
Part E: Draw and Label
Draw a simple circuit with a battery, switch, and bulb. Show the direction of current.
✅ Detailed Solutions – Section 5 Handout
Part A: Fill in the Blanks
1
Flow of charge is called electric current.
2
We measure current using an ammeter.
3
V = I × R is called Ohm's law.
4
Power is measured in watts (W).
5
A fuse melts when current is too high.
Part B: True or False
1
False. Current is measured in ampere (A), not volts. Volts measure voltage.
2
True. A thicker wire has a larger cross-sectional area, so it offers less resistance.
3
False. In series, total resistance = R1 + R2 + R3 — it increases, not decreases.
4
True. P = V × I gives power in watts.
5
True. MCB (Miniature Circuit Breaker) is a safety switch that trips off on high current.
Part C: Solved Problems
Problem 1 — V = 6 V, R = 2 Ω. Find current.
1
Formula: V = I × R → I = V ÷ R.
2
I = 6 ÷ 2 = 3.
Answer: Current I = 3 A.
Problem 2 — Fan uses 2 A at 220 V. Find power.
1
Formula: P = V × I.
2
P = 220 × 2 = 440.
Answer: Power = 440 W.
Part D: Match the Columns
1
Ammeter → b. Measures current
2
Voltmeter → a. Measures voltage
3
Fuse → d. Safety device
4
Ohm's Law → c. V = I × R
Part E: Simple Circuit Description
1
Draw a rectangle. Place the battery (two lines — long positive, short negative) on the left side.
2
Place the switch (a gap with a diagonal line) on the top wire.
3
Place the bulb (circle with a cross) on the right side.
4
Connect with wires to form a closed rectangular loop.
Current flows from the positive terminal of the battery → through the switch → through the bulb → back to the negative terminal. Conventional current direction: + to −.
🎴 Section 6 — Revision Flashcards
What is electric current?
Flow of electric charge through a wire.
What does Ohm's law say?
V = I times R (voltage = current times resistance).
What is resistance?
It slows down the flow of current.
How do series resistors add?
R total = R1 + R2 + R3 (just add).
What is electric power?
How fast energy is used. P = V times I.
What is a kilowatt-hour?
Unit for energy used in electricity bills.
What does a fuse do?
It melts and breaks the circuit if current is too high.