Schooling · Class 10 · Science · Electricity · Chapter on a page
CBSE Class 10 · Science · NCERT Science
Electricity: chapter on a page
A cut of Shishya's notes for this chapter: the first paragraph of the introduction and the key ideas, formulas and facts, common mistakes and quick revision lists, word for word. Nothing is added or reworded; the worked examples are left out (they are on the chapter page).
About the notes: Written by Shishya's AI on 26 Sept 2026 from the chapter's title and class level, in Shishya's own words — not a copy or summary of the textbook. Read the official chapter for the book's own text, activities and exercises.
This note's current text has no applied fact-check on record.
Mind map
Drawn from the same notes by a fixed rule (no AI): each label is the item's own words — its bold term, its label before a colon, a short formula as written, or its first words.
The mind map as a list
- Key ideas
- Electric current is the rate of flow…
- Potential difference between two…
- Ohm's law states that the current…
- Resistance is the property of a…
- The resistance of a conductor…
- In a series combination, the…
- In a parallel combination, the…
- Formulas and facts
- I = Q/t
- V = W/Q
- V = IR
- R = ρL/A
- Series resistance
- Parallel resistance
- P = VI = I²R = V²/R
- Watch out for
- Confusing current with charge
- Adding resistances in parallel…
- Forgetting that the same current…
- Mixing up watts and kilowatt-hours
- Using wrong units for resistivity…
What this chapter is about
This chapter introduces the fundamental concepts of current electricity. You learn what electric current is, how it flows through conductors, and what makes it flow. The chapter builds your understanding of electric potential, potential difference, and the relationship between current and voltage.
Key ideas
- Electric current is the rate of flow of electric charge through a conductor; its SI unit is the ampere (A), where 1 A = 1 coulomb per second.
- Potential difference between two points is the work done to move a unit positive charge from one point to another; its SI unit is the volt (V).
- Ohm's law states that the current through a metallic conductor is directly proportional to the potential difference across it, provided temperature remains constant: V = IR.
- Resistance is the property of a conductor that opposes the flow of current; its SI unit is the ohm (Ω).
- The resistance of a conductor depends on its length (directly), cross-sectional area (inversely), the material (resistivity), and temperature.
- In a series combination, the equivalent resistance equals the sum of individual resistances: R = R₁ + R₂ + R₃.
- In a parallel combination, the reciprocal of equivalent resistance equals the sum of reciprocals: 1/R = 1/R₁ + 1/R₂ + 1/R₃.
- Electric power is the rate of doing electrical work: P = VI = I²R = V²/R, measured in watts (W).
Formulas and facts to remember
- Current: I = Q/t, where Q is charge in coulombs and t is time in seconds.
- Potential difference: V = W/Q, where W is work done in joules.
- Ohm's law: V = IR, or equivalently I = V/R and R = V/I.
- Resistance of a wire: R = ρL/A, where ρ is resistivity, L is length, A is cross-sectional area.
- Series resistance: R_total = R₁ + R₂ + R₃ + ...
- Parallel resistance: 1/R_total = 1/R₁ + 1/R₂ + 1/R₃ + ...
- Electric power: P = VI = I²R = V²/R, unit is watt (W).
- Electrical energy: E = Pt = VIt, unit is joule (J); commercial unit is kilowatt-hour (kWh), where 1 kWh = 3.6 × 10⁶ J.
Common mistakes
- Confusing current with charge → Current is the rate of flow of charge, not charge itself; use I = Q/t.
- Adding resistances in parallel directly → In parallel, add reciprocals first, then take the reciprocal of the sum.
- Forgetting that the same current flows through all components in series → In series circuits, current is constant; voltage divides.
- Mixing up watts and kilowatt-hours → Watt measures power (rate of energy use); kWh measures total energy consumed.
- Using wrong units for resistivity calculations → Ensure length is in metres, area in square metres, and resistivity in Ω·m.
Quick revision
- Current (I) = Charge (Q) ÷ Time (t); unit is ampere.
- Ohm's law: V = IR; valid when temperature is constant.
- Series: same current, resistances add; Parallel: same voltage, reciprocals add.
- Power = Voltage × Current; Energy = Power × Time.
- 1 kWh = 1000 W used for 1 hour = 3.6 × 10⁶ J.
- Resistance increases with length; decreases with thicker wire.