Tuesday, May 23, 2023

What is Current?

Current, in the context of electrical circuits, refers to the flow of electric charge through a conductor. It is the rate at which electric charges, typically electrons, move past a given point in a circuit. Current is measured in units called Amperes (A) and is denoted by the symbol "I."

Fig. 1 free electrons 
cited from: https://circuitglobe.com/electric-current.html 
Fig. 2 Flow of electron
cited from: https://circuitglobe.com/electric-current.html 

In simple terms, current is the flow of electrons or charge in a closed loop circuit. It is similar to the flow of water in a pipe. Just as water flows from a higher pressure to a lower pressure, electric current flows from a region of higher electric potential (voltage) to a region of lower electric potential.

There are two types of current:

  1. Direct Current (DC): In a DC circuit, the flow of electric charge is unidirectional. The magnitude and direction of the current remain constant over time. Batteries and most electronic devices operate on DC.
  2. Alternating Current (AC): In an AC circuit, the flow of electric charge periodically changes direction. The magnitude and direction of the current vary sinusoidally with time. AC is commonly used for power distribution in homes and businesses.

Fig. 3 Analogy 
(link from https://eschooltoday.com/learn/wp-content/uploads/2020/10/explain-current-and-voltage.jpg)

The behavior of current in a circuit is governed by Ohm's Law, which states that the current (I) flowing through a conductor is directly proportional to the voltage (V) across the conductor and inversely proportional to its resistance (R). Mathematically, Ohm's Law can be expressed as:

I = V / R

where: I = Current (in Amperes) V = Voltage (in Volts) R = Resistance (in Ohms)

Current is a fundamental quantity in electrical circuits and plays a crucial role in determining the behavior and operation of various electronic components and devices.

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