Science · Class 10
Electricity
Ohm's law, resistance, series-parallel circuits, and electrical power.
4 sections15–25 min read6 MCQs · 2 examples
Chapter Overview
Electric current is flow of charge; potential difference drives it through resistance. Ohm's law, series and parallel circuits, electrical power, heating effect, and domestic circuits are covered.
Core Relations
Current
I = Q/t (Ampere = C/s)
Ohm's law
V = IR
Resistance
R = ρL/A
Resistors in series
R_eq = R₁ + R₂
Resistors in parallel
1/R_eq = 1/R₁ + 1/R₂
Power
P = VI = I²R = V²/R
Electrical energy
E = Pt = VIt
Heating Effect
- Joule heating: H = I²Rt
- Fuse wire melts on overcurrent
- Electric iron, heater, geyser use this effect
Domestic Circuit
- Live (red), neutral (black), earth (green)
- 220 V AC in India
- Parallel connections for appliances
Solved Examples
Step-by-step solutions — read each step before checking the final answer.
Ohm's law
R=20Ω, V=10V. Find I and P.
- 1I = V/R = 0.5 A
- 2P = VI = 5 W
Answer
I=0.5 A, P=5 W
Parallel resistance
Two 10Ω resistors in parallel. R_eq?
- 11/R = 1/10 + 1/10 = 2/10
- 2R_eq = 5 Ω
Answer
5 Ω
Key Points to Remember
- ✓ Ammeter in series; voltmeter in parallel
- ✓ 1 kWh = 3.6×10⁶ J
- ✓ Resistivity depends on material and temperature
Exam Tips
- • Draw circuit before solving
- • Check series vs parallel
- • Show formula substitution for numericals
Practice MCQs — Electricity
Test your understanding with topic-wise multiple choice questions. Explanations appear after each answer.
Question 1 of 6Score: 0/0
SI unit of current: