CBSE Class 10 Science Chapter 11 Notes of Electricity PDF

Many students feel stressed about solving complex circuits, remembering formulas, and applying Ohm’s Law correctly as the CBSE Class 10 board exam on February 25, 2026 approaches. Trying to memorize every derivation or calculation at the last minute can be confusing, especially when high-weightage numericals appear in the exam hall.

Class 10 Electricity Notes solve this problem by providing a simple, exam-focused plan. Instead of long theory, these notes concentrate on the “must-know” formulas for current, voltage, resistance, and power, easy step-by-step methods for solving series and parallel circuits, and shortcuts for calculating equivalent resistance.

By focusing on topics that frequently appear in board papers, like Ohm’s Law applications, Joule’s heating effect, and energy consumption, these notes help students revise quickly. This ensures that even the toughest numerical or conceptual questions in electricity can be solved confidently in the final hours before the exam.

What is Electricity?

Electricity is the flow of electric charge. It is a fundamental part of our daily lives.

These notes explore the basic principles of electricity and its effects. Understanding these concepts is vital for students studying physics in Class 10. The notes cover definitions, laws, and practical applications.

Electricity Class 10 Notes

Electricity Class 10 Notes provide a concise explanation of important concepts such as electric current, Ohm’s Law, resistance, electric power, and energy for easy understanding.

These notes are designed for quick revision and help students prepare effectively for CBSE exams with key formulas and numericals.

1. Fundamentals of Electric Charge and Current

Electric Charge (Q)

At its most basic level, electricity begins with the concept of electric charge. There are two types of electric charges: positive and negative.

• Fundamental Principles: Like charges repel each other, while unlike charges attract each other.

• SI Unit: The SI unit of electric charge is the Coulomb (C).

• Fundamental Charge: The smallest independent charge is the charge of a single electron, denoted by e, which is approximately 1.6 × 10⁻¹⁹ C.

Electric Current (I)

Electric current is defined as the rate of flow of positive electric charge through a conductor.

• Formula:
  
  where I is current, Q is charge, and t is time.
  
  

• SI Unit: The SI unit of electric current is the Ampere (A).

• Direction of Current: By convention, the direction of electric current is taken as opposite to the direction of flow of electrons.

• Measurement: Electric current is measured using an Ammeter, which is always connected in series in a circuit.
  
  

Potential Difference and Resistance

Potential Difference (V)

Potential difference (also called voltage) between two points in an electric circuit is defined as the amount of work done in moving a unit charge from one point to another.

• Formula:
  
  where W is the work done (in joules) and Q is the charge.
  
  

• SI Unit: The SI unit of potential difference is the Volt (V).

• Flow Direction: Conventional current flows from a point of higher potential to lower potential, whereas electrons flow from lower potential to higher potential.

• Measurement: Potential difference is measured using a Voltmeter, which is connected in parallel across the component.

Resistance (R) and Resistivity (ρ)

Resistance is the property of a conductor that opposes the flow of electric current through it.

Factors Affecting Resistance

1. Length (L): Resistance is directly proportional to the length of the conductor
   

2. Area of Cross-section (A): Resistance is inversely proportional to the cross-sectional area
   

3. Material: Different materials have different resistance depending on their nature.

4. Temperature: In metals, resistance generally increases with an increase in temperature.
   
   

Resistivity (ρ)

Resistivity is a characteristic property of a material and does not depend on the length or area of the conductor. Materials like metals have low resistivity, while insulators such as rubber and glass have very high resistivity.

• SI Units:
  
  

• Resistance → Ohm (Ω)

• Resistivity → Ohm-metre (Ω m)

Ohm’s Law

Ohm’s Law states that the potential difference (V) across the ends of a metallic conductor is directly proportional to the current (I) flowing through it, provided the temperature remains constant.

• Mathematical Expression:
  

• Graphical Representation:
  A V–I graph for an ohmic conductor is a straight line passing through the origin. The slope of this graph represents the resistance (R) of the conductor.

Combinations of Resistors

In electric circuits, resistors are commonly connected in series or parallel.

Series Combination

In a series combination, resistors are connected end-to-end so that the same current flows through each resistor.

• Equivalent Resistance:

• Key Property:
  The current remains the same throughout the circuit, but the total potential difference is divided among the resistors.
  
  

Parallel Combination

In a parallel combination, resistors are connected across the same two points, providing multiple paths for current flow.

• Equivalent Resistance:
  

Advantages of Parallel Combination

1. Independence: If one appliance fails, the others continue to work.
   
   

2. Specific Current Requirement: Different devices can draw different amounts of current as needed.
   
   

3. Reduced Resistance: The total resistance of the circuit is less than the smallest individual resistance, making it more efficient.
   
   

Electric Power

Electric power (P) is the rate of consuming electric energy. The SI unit of power is Watt (W).

P = VI

Electric energy (E) supplied by a source is E = P x t. The commercial unit of energy is kilowatt-hour (kWh).

Heating Effect of Electric Current

When current passes through a conductor, it heats up. This is the heating effect of electric current.

Joule’s Law of Heating

According to Joule’s law, the heat produced (H) in a resistor is:

1. Directly proportional to the square of the current (I²).

2. Directly proportional to the resistance (R).

3. Directly proportional to the time (t) for which current flows.
   
   

• Formula:
  

Applications of Heating Effect

Practical Applications of Heating Effect

• Electric Appliances: Devices like electric irons, heaters, kettles, and ovens work on the heating effect of electric current.

• Electric Bulbs: The filament, usually made of tungsten due to its high melting point, becomes white-hot and emits light.

• Electric Fuse: A fuse is a safety device made of a wire with a low melting point. It melts when excessive current flows, breaking the circuit and preventing damage to appliances and fire hazards.

Circuit Symbols

Electrical components are shown using specific symbols in circuit diagrams.