Electric Current

Introduction

• Concept: Electric current is the flow of electric charge in a conductor.
• Simplification: Current means flow, e.g., water current (air current - wind)
• Electric Current: Flow of charge in a conductor.

Basic Concept

• Current: Flow of electric charges in a conductor's cross-sectional area in 1 second.
• Formula:
  • Represented by 'I'.
  • I = Q / t (where Q is charge, t is time)
  • SI Unit: Ampere (A)
• 1 Ampere: 1 Coulomb of charge passing through a conductor in 1 second.

Steady Current

• Definition: A current where the rate of flow of charge remains constant over time.
• Example: A constant 10 Coulomb charge flowing per second continuously.
• Formula:
  • Steady current remains constant, maintaining the same rate of charge flow.

Scalar Quantity of Current

• Current, although it seems directional, is a scalar quantity because it doesn't follow vector addition rules but follows simple arithmetic addition.
• Example: 10A + 10A = 20A irrespective of the direction.

Types of Electric Current

• Electronic Current: Due to the flow of electrons, real current.
• Conventional Current: Hypothetical current due to the positive charge flow.

Electronic Current

• Flow of Electrons: From negative terminal to positive terminal.
• Example: Battery scenario.

Conventional Current

• Traditional View: Initially believed that current is due to positive charge flow.
• Effect: Same as electron flow but in opposite direction (positive to negative).
• Reason: Historical misconception; electrons can't flow when believed to be positive.
• Polarity: Positive is high potential; Negative is low potential.

Illustrations and Definitions

• Comparison of Effects: Movement of electrons (right to left) creates the same effect as positive charges moving (left to right).
• Connector Example: Moving electrons create positive charge at one end.

Nature of Current in Metallic Conductors

• Random Motion: Free electrons are in random motion without battery connection.
• With Battery Connection: Electrons move in a specific direction, creating current.

Direct Current (DC) vs Alternating Current (AC)

• Direct Current (DC): Unidirectional flow of current (e.g., from a battery).
• Alternating Current (AC): Current changes direction periodically (e.g., from a power outlet).
• AC Characteristics: Fluctuates with time, maintaining high frequency (e.g., 50 Hz).
• Graphical Representation:
  • DC: Straight line, continuous in one direction.
  • AC: Sinusoidal wave, alternating between positive and negative values.

Current Flow Types

• Through Metals: Due to free electrons.
• Through Electrolytes: Due to positive and negative ions; can include both ionic and free electron movement.