Class 10 Science – Electricity

Class 10 Science Chapter 11: Concepts

Chapter 11: Electricity

Introduction

Electricity is a fundamental form of energy that powers our daily lives. It is based on the movement of electric charges and is used in various applications, from lighting our homes to running electrical appliances. Understanding the basic principles of electricity, such as electric current, resistance, and power, is essential.

Electric Charge and Current

A. Electric Charge

  • Charge is a fundamental property of matter.
  • There are two types of charges: positive (+) and negative (-).
  • Like charges repel each other, while unlike charges attract.

B. Electric Current (I)

  • The flow of electric charge is called electric current.
  • It is measured in amperes (A).
  • Formula: , where
    • = current (A),
    • = charge (Coulombs, C),
    • = time (seconds, s).
Diagram: Electric Current in a Circuit

Electric Potential and Potential Difference

A. Electric Potential

  • It is the amount of work done to move a unit charge from infinity to a point.
  • Measured in volts (V).

B. Potential Difference (Voltage, V)

  • The difference in electric potential between two points in a circuit.
  • Formula: , V = W/Q, where
    • = potential difference (V),
    • = work done (Joules, J),
    • = charge (C).
Diagram: Representation of Potential Difference

Ohm’s Law

Ohm’s Law states that the current flowing through a conductor is directly proportional to the voltage applied across it and inversely proportional to its resistance.

Formula:

where,

  • = potential difference (volts, V),
  • = current (amperes, A),
  • = resistance (ohms, Ω).
Graph: Voltage vs. Current (Ohm’s Law)

Resistance and Factors Affecting It

A. Resistance (R)

  • It is the property of a conductor that opposes the flow of current.
  • Measured in ohms (Ω).

B. Factors Affecting Resistance

  1. Length (L): Resistance increases with length.
  2. Cross-sectional Area (A): Resistance decreases with a larger area.
  3. Material: Different materials have different resistances.
  4. Temperature: Higher temperatures increase resistance.
Diagram: Factors Affecting Resistance

Resistances in Series and Parallel

A. Resistors in Series

  • Total resistance:
  • The same current flows through all resistors.

B. Resistors in Parallel

  • Total resistance:
  • Voltage remains the same across all resistors.
Diagram: Series and Parallel Circuits

Heating Effect of Electric Current (Joule’s Law)

When an electric current flows through a conductor, some of the electrical energy is converted into heat energy.

Formula:

H = I2 Rt where,

  • = heat energy (Joules, J),
  • = current (A),
  • = resistance (Ω),
  • = time (s).
Applications:
  • Electric heaters
  • Electric iron
  • Filament bulbs
Diagram: Heating Effect of Current

Electric Power and Energy

A. Electric Power (P)

  • The rate at which electrical energy is consumed.
  • Formula: or or . P = VIP = I2 R and P = V2/R.
  • Measured in watts (W).

B. Electrical Energy

  • The total work done by an electric current.
  • Formula: .
  • Measured in joules (J) or kilowatt-hour (kWh).
Diagram: Power Calculation in a Circuit
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