Here are well-organized notes for Class 10 Science — Chapter: Electricity, based on the NCERT book, considering CBSE Board Exam patterns & topic-wise previous year questions.
📖 Notes: Chapter — Electricity
🔷 Key Concepts:
1️⃣
Electric Current
- The flow of electric charge.
- Denoted by I, measured in amperes (A).
- I = \frac{Q}{t}
Q = charge (Coulombs), t = time (seconds).
2️⃣
Electric Potential & Potential Difference
- Work done per unit charge to move a charge between two points.
- Potential difference V = \frac{W}{Q}
- Unit: volt (V).
3️⃣
Ohm’s Law
- At constant temperature:
V \propto I → V = IR
where R = resistance. - Resistance R: property of a conductor to oppose flow of charge.
Unit: ohm (Ω).
4️⃣
Resistance & Resistivity
- R = \rho \frac{l}{A}
- l: length of conductor.
- A: area of cross-section.
- \rho: resistivity (material property).
- Resistivity depends on material & temperature, unit: \Omega m.
5️⃣
Factors Affecting Resistance
✅ Directly proportional to length
✅ Inversely proportional to area
✅ Depends on material
✅ Increases with temperature (in metals).
6️⃣
Combination of Resistors
- Series:
R_{eq} = R_1 + R_2 + R_3 + …
Current same, voltage divides. - Parallel:
\frac{1}{R_{eq}} = \frac{1}{R_1} + \frac{1}{R_2} + …
Voltage same, current divides.
7️⃣
Electrical Power & Energy
- Power P = VI = I^2R = \frac{V^2}{R}
Unit: watt (W). - Energy: E = Pt = VIt
Unit: kilowatt-hour (kWh).
8️⃣
Heating Effect of Electric Current
- Heat produced: H = I^2Rt (Joule’s law of heating)
- Applications: electric heater, bulb, fuse, etc.
📋
Topic-wise Previous Year Questions
(Frequently asked in CBSE Class 10 Board Exams)
🌟 Short Answer Type (1–2 marks)
✅ Define electric current & its unit.
✅ State Ohm’s law.
✅ Define resistivity & mention its SI unit.
✅ Why is tungsten used in electric bulbs?
✅ Why is fuse wire made of a low melting point material?
✅ What is the advantage of connecting resistors in parallel in household circuits?
🌟 Short Answer Type-II (3 marks)
✅ Derive the expression for equivalent resistance in series and parallel.
✅ Three resistors of 2Ω, 3Ω, and 6Ω are connected in parallel. Find total resistance.
✅ Explain heating effect of current & its applications.
✅ How does resistance of a conductor depend on length, area & temperature?
🌟 Long Answer Type (5 marks)
✅ With diagram, explain series & parallel combinations of resistors with one example.
✅ Derive the formula H = I^2Rt for heat produced & explain applications.
✅ An electric bulb is rated 220V, 100W. Find its resistance & current drawn.
✅ Draw circuit diagram to verify Ohm’s law & explain the procedure.
🌟 Diagram-based Questions
✅ Circuit diagram for Ohm’s law experiment.
✅ Circuit showing resistors in series and parallel.
✅ Graph of V vs I showing linear relation.
🌟 Numerical Questions (commonly asked)
🔷 A current of 2A flows through a 5Ω resistor for 10 minutes. Find heat produced.
🔷 Two resistors of 6Ω and 12Ω are connected in series with 12V battery. Find current & potential difference across each.
🔷 A 100W bulb is used for 10 hours. Find energy consumed in kWh & cost at ₹5 per unit.
📌 Tips for Exam:
✔ Write Ohm’s law clearly with graph & circuit.
✔ Memorize series & parallel formulas.
✔ Practice numericals regularly.
✔ Draw neat diagrams where asked.
✔ Learn definitions like current, potential, resistivity, etc., word-to-word.
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