An electric current is said to exist when there is a net flow of electric charge through a region. In electric circuits this charge is often carried by electrons moving through a wire. ... The moving charged particles in an electric current are called charge carriers.

Introduction:
Electric current is the flow of electric charge in a closed circuit. It is driven by a voltage source, such as a battery or a power supply, and is essential for the functioning of various electrical devices and systems. Understanding how electric current flows in a circuit is fundamental to grasp the principles of electricity.

Electric Circuit:
An electric circuit consists of various components connected in a closed loop or pathway. These components typically include a voltage source, conductors (such as wires), and loads (such as light bulbs or resistors). The circuit provides a complete path for the flow of electric charge.

Electric Charge:
Electric charge is carried by subatomic particles called electrons. Electrons have a negative charge and are loosely bound to atoms. In a conductive material, such as a metal wire, electrons are free to move and are responsible for carrying electric charge.

Voltage Difference:
The driving force behind the flow of electric charge is the voltage difference across the circuit. Voltage is the potential energy per unit charge, and it is measured in volts (V). A voltage source, like a battery, creates a potential difference between its terminals, which causes electrons to move from the negative terminal (higher potential) to the positive terminal (lower potential).

Flow of Electric Current:
When a circuit is closed, meaning it forms a complete loop, the voltage difference creates an electric field that exerts a force on the electrons. This force causes the free electrons in the conductive material to move in response to the electric field. As one electron moves, it displaces another electron, creating a chain reaction that results in a continuous flow of charge.

Direction of Electric Current:
Conventionally, the direction of electric current is considered to be from the positive terminal to the negative terminal, opposite to the actual flow of electrons. This convention was established before the discovery of the electron and is still used for consistency.

Factors Affecting the Flow of Electric Current:
The flow of electric current in a circuit is influenced by several factors:

1. Resistance: Conductive materials have varying levels of resistance to the flow of electric charge. Higher resistance reduces the current flow, while lower resistance allows for a greater flow.

2. Ohm's Law: The relationship between voltage (V), current (I), and resistance (R) is defined by Ohm's law: V = I * R. It states that the current in a circuit is directly proportional to the voltage and inversely proportional to the resistance.

3. Series and Parallel Connections: Components in a circuit can be connected in series or parallel. In a series circuit, the same current flows through each component, while in a parallel circuit, the current divides among the branches.

Conclusion:
Electric current flows in a closed circuit due to the presence of a voltage difference. The voltage drives the movement of electrons, which carry the electric charge through conductive materials. Understanding the flow of electric current is crucial in designing and analyzing electrical systems.