Electricity

Electricity is the flow of electric charge, typically carried by electrons moving through a conductor such as a wire. It is a form of energy resulting from the existence and movement of charged particles like electrons or ions.

Electricity Electricity

Electric Current and Charge Flow


Electricity originates from the movement of electric charge, primarily electrons, through a conductor.



Direct Current (DC)


Direct Current (DC) is an electric current that flows in one constant direction. Unlike AC, which periodically reverses direction, DC maintains a steady flow of electrons from the negative terminal to the positive terminal of a power source.

I=QtI = \frac{Q}{t}

Where:

  • I= current (in amperes),

  • Q = electric charge (in coulombs),

  • t = time (in seconds)


Sources of Direct Current


Direct Current (DC) electricity can be generated from various sources. One of the most common sources is chemical sources, such as batteries and cells. Examples include dry cells used in flashlights and lead-acid batteries found in automobiles. These devices rely on electrochemical reactions that create a potential difference, causing electrons to flow in one direction and produce DC.

Another source is the DC generator, which works by converting mechanical energy into electrical energy. It uses a component called a commutator to ensure that the current flows in a unidirectional manner. Lastly, solar cells serve as a clean and sustainable source of DC electricity. They function based on the photovoltaic effect, which allows them to convert solar energy directly into electrical energy without any moving parts or chemical reactions.

DC Current DC Current

Characteristics of Direct Current



  • Constant polarity: One terminal remains positive, the other negative.

  • Unidirectional flow: Electrons move in a single direction.

  • Stable voltage and current: Ideal for devices needing consistent energy input.

  • Easily stored in batteries for future use.


Characteristics of DC Current Characteristics of DC Current

Graph of DC vs Time


A DC voltage/time graph is a straight horizontal line, indicating a constant voltage over time.

DC Voltage with Time DC Voltage with Time

Types of Direct Current



  1. Pure DC – Completely constant magnitude (ideal case)

  2. Pulsating DC – Varies in magnitude but does not reverse direction (commonly from rectifiers)


Pure and Pulsating DC Pure and Pulsating DC

Difference Between DC and AC





































Feature Direct Current (DC) Alternating Current (AC)
Direction Flows in one direction Reverses direction periodically
Source Batteries, solar cells Generators, power stations
Transmission Poor over long distance Efficient over long distances
Frequency Zero 50 Hz (India), 60 Hz (US)
Applications Electronics, EVs Household power, heavy appliances

Read: Science Notes