Wrong shortcode initialized

I. Chapter Summary

This chapter introduces the concept of electric current, its causes, and effects. Students learn about potential difference, Ohm’s Law, resistance, resistivity, resistors in series and parallel, and the heating effect of electric current. The chapter emphasizes understanding how electric energy is measured and provides the basis for electrical applications in daily life and industries.

II. Key Concepts Covered

Concept	Explanation
Electric Current (I)	Flow of electric charge; measured in amperes (A).
Potential Difference (V)	Work done per unit charge to move the charge between two points. Unit: volt (V).
Ohm’s Law	V=IRV = IRV=IR: Voltage is directly proportional to current at constant temperature.
Resistance (R)	Opposition offered by a conductor to the flow of current. Unit: ohm (Ω).
Resistivity (ρ)	Material property; $ρ=R⋅Al rho = R cdot frac{A}{l}ρ=R⋅lA​; unit: ohm-meter (Ω·m).$
Series Combination of Resistors	$Rtotal=R1+R2+R3+…R_ {text{total}} = R_1 + R_2 + R_3 + l​=R1​+R2​+R3​+…$
Parallel Combination of Resistors	$1Rtotal=1R1+1R2+… frac{1}{R_{text{total}}} = frac{1}{R_1} +  frac{1}{R_2} + ​1​=R1​1​+R2​1​+…$
Electric Power (P)	$P=VI=I2R=V2RP = VI = I^2R = frac{V^2} {R}P=VI=I2R=RV2$​; unit: $watt (W).$
Electrical Energy	$E=Pt=VItE = Pt = VItE=Pt=VIt;$ commercial unit: kilowatt-hour (kWh).
Heating Effect of Current	$H=I2RtH = I^2RtH=I2Rt:$ Basis of devices like electric heaters, toasters, etc.

III. Important Questions

(A) Multiple Choice Questions (1 Mark)

1. Which of the following is the SI unit of electric current?
   a) Coulomb
   b) Volt
   c) Ohm
   d) Ampere ✅ (PYQ 2020)
2. Which physical quantity is expressed in kWh?
   a) Current
   b) Power
   c) Energy ✅ (PYQ 2019)
   d) Resistance
3. Which resistor arrangement has higher equivalent resistance?
   a) Series ✅
   b) Parallel
   c) Both same
   d) Cannot say
4. Ohm’s Law is valid when:
   a) Temperature varies
   b) Temperature remains constant ✅ (PYQ 2018)
   c) Resistance varies
   d) Voltage is zero

(B) Short Answer Questions (2/3 Marks)

1. State Ohm’s Law. How can it be verified experimentally?
2. Differentiate between series and parallel combination of resistors.
3. Write the formula for calculating electrical energy consumed in a household and define each term.
4. A wire of resistance 10 Ω carries a current of 2 A. Calculate the heat produced in 5 minutes.

(C) Long Answer Questions (5 Marks)

1. Explain the heating effect of electric current. Derive the expression for heat produced. List two applications.
2. A bulb is rated 100 W, 220 V. Find:
    a) Its resistance
    b) The current drawn by it
    c) The energy consumed if used for 10 hours.
3. Three resistors of 3 Ω, 6 Ω, and 9 Ω are connected in parallel. Calculate the total resistance and current if connected to a 9V battery.
4. What is electric power? Derive three expressions for electric power. Also explain the commercial unit of energy.

(D) HOTS (Higher Order Thinking Skills)

1. Why is parallel arrangement preferred in domestic wiring?
2. If the resistivity of a wire doubles and its length is halved, what will happen to its resistance?

IV. Key Formulas/Concepts

Formula	Description
$I=QtI = frac{Q}{t}I=tQ​$	Current = Charge / Time
$V=IRV = IRV=IR$	Ohm’s Law
$R=ρ⋅lAR = rho cdot frac{l}{A}R=ρ⋅Al​$	Resistance in terms of resistivity
$Rseries=R1+R2+…R_{text{series}}$ = $R_1 + R_2 + dotsRseries​=R1​+R2​+…$	Series combination
$1Rparallel=1R1+…frac{1}{R_{text{parallel}}} = frac{1}{R_1} + dotsRparallel​1​=R1​1​+…$	Parallel combination
$P=VI=I2R=V2RP = VI = I^2R = frac{V^2}{R}P=VI=I2R=RV2​$	Electric power
$H=I2RtH = I^2RtH=I2Rt$	Heat produced due to current
$E=P×tE = P times tE=P×t$	Electrical energy
$1 kWh=1000 W×3600 s=3.6×106 J1 text{ kWh} = 1000 text{ W} times 3600 text{ s} = 3.6 times 10^6 text{ J}1 kWh=1000 W×3600 s=3.6×106 J$	Commercial unit

V. Deleted Portions (CBSE 2025–2026)

 No portions have been deleted from this chapter as per the rationalized NCERT textbooks.

VI. Chapter-Wise Marks Bifurcation (Estimated – CBSE 2025–2026)

Unit/Chapter	Estimated Marks	Type of Questions Typically Asked
Chapter 11: Electricity	12–14 Marks	1 Long Answer, 2 Numericals, 1 Diagram, MCQs

VII. Previous Year Questions (PYQs)

Year	Marks	Question
2021	1	Define SI unit of electric current. (Ampere)
2020	3	Differentiate series and parallel combinations with diagrams.
2019	5	Derive the formula for heat produced by electric current.
2018	1	State the condition for Ohm’s Law to be valid. (Temperature constant)

VIII. Real-World Application Examples to Connect with Topics

Concept	Application
Ohm’s Law	Designing electronic circuits and testing electrical appliances
Series/Parallel Circuits	Used in domestic wiring, fuse design, and batteries
Electric Heating	Devices like irons, geysers, toasters
Electric Power & Energy	Household energy bills, rating of appliances

IX. Student Tips & Strategies for Success

Time Management

• Practice 2 numericals and 1 derivation daily.
• Dedicate weekly time for solving diagrams and labeling.

Exam Preparation

• Create a formula chart for quick revision.
• Practice PYQs and NCERT exemplar problems thoroughly.
• Understand significance of units in numericals (especially Joules vs kWh).

Stress Management

• Use real-life electrical appliance examples to understand power and energy.
• Attempt numericals step-by-step to avoid calculation anxiety.

X. Career Guidance & Exploration (Class-Specific)

For Classes 9–10

Streams

• Science: Electrical Engineering, Electronics, Physics
• Commerce: Electrical Product Business, Technical Sales
• Arts: Technical Writing, Energy Journalism

Career Options

• Electrical Engineer, Electrician, Renewable Energy Technician, Energy Auditor

Entrance Exams

• NTSE, NSO, Junior Science Olympiad, KVPY (Class 11+)

XI. Important Notes

• Refer to https://cbseacademic.nic.in and https://ncert.nic.in for official syllabus updates.
• Emphasize clarity in formulas, units, and diagrams.
• Understanding basic concepts like Ohm’s Law and energy consumption can help in real-life decisions like choosing appliances.