Electricity (Class 10)
About 6 min · Science · English
Time worked out from the lesson's 357 words at 150 words a minute, plus a minute for each question.
This chapter forms the foundation for understanding electric circuits, household wiring, and power consumption—concepts tested through numerical problems, circuit analysis, and conceptual questions.
Key ideas
- Electric Current: Flow of electric charge through a conductor, measured in amperes (A). Direction of conventional current is opposite to electron flow. 1 ampere = 1 coulomb per second (1 A = 1 C/s).
- Electric Potential and Potential Difference: Work done per unit charge to move charge between two points. Measured in volts (V). 1 volt = 1 joule per coulomb (1 V = 1 J/C). Potential difference drives current flow.
- Resistance: Opposition to current flow in a conductor, measured in ohms (Ω). Depends on length (directly proportional), cross-sectional area (inversely proportional), temperature, and material (resistivity ρ).
- Ohm's Law: At constant temperature, current through a conductor is directly proportional to potential difference across it: V = IR. This relationship holds for ohmic conductors (metals) but not for devices like diodes or transistors.
- Series Circuit: Components connected end-to-end in a single path. Same current flows through all components. Total voltage divides across components. Total resistance equals sum of individual resistances.
Quick reference
- Ohm's Law: V = IR (foundation formula—memorize variants I = V/R and R = V/I)
- Series: Same current, voltages add, resistances add directly (R_total = R₁ + R₂ + ...)
- Parallel: Same voltage, currents add, use reciprocal formula (1/R_total = 1/R₁ + 1/R₂ + ...)
- Power trio: P = VI = I²R = V²/R (choose based on given quantities)
- Energy cost: Energy (kWh) = Power (kW) × Time (h), then multiply by rate per kWh
Check yourself: 3 questions
1. A wire of resistance 10 Ω is connected across a battery of 5 V. What is the current flowing through the wire?
2. Three resistors of 2 Ω, 3 Ω, and 5 Ω are connected in series. What is the total resistance of the combination?
3. Two resistors of 6 Ω and 3 Ω are connected in parallel. A potential difference of 12 V is applied across the combination. What is the total current drawn from the source?
This lesson is cut from the topic's note, not rewritten. Fact-checked on 21 Oct 2026: an AI-assisted check of this note against cited sources; the errors it found were corrected that day. Some errors may remain. The questions are from Shishya's validated question bank.
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