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**Voltage** and **current** both are important aspects of an electrical circuit, that’s why one need to understand about these terms. Both of them are essentially required to drive an electrical circuit.

**VOLTAGE AND CURRENT CONCEPT**

**CURRENT**

**Current **is something that is flowing like water flowing in river is known as water current and for wind we say air current is high or low today, similar to these

**Electric Current **is the rate of flow of electric charge (electrons) in a closed circuit. Electric current will divide in parallel branches (different in different loops or mesh) of a circuit while remaining the same in one loop (mesh) of a circuit. Current also follows a low resistive path.

The symbol for current is the letter *“I”*. The SI (Système international) unit is the Ampere, denoted by *“A”*. In simple words charge particles (electrons) flow in a direction in a closed circuit which causes electric current in a circuit.

__NOTE__** : **It is interesting to know

*Electrons flow**from the negative terminal to the positive. Conventionally,*

**Current flows**from the positive terminal to the negative.**VOLTAGE**

** Voltage** is also called an electromotive force. It is actually the **potential difference **of charges across two points/nodes/terminals in an electrical circuit. Voltage will drop in series resistance while the same in parallel branches of resistance, what we measure is actually voltage drop across load.

Voltage is present in an open circuit, that’s why when we insert line tester in plug but didn’t touch behind, it will not lead the LED glow but as we touched it, LED glows up and shows that line is active.

Voltage is denoted by the letter *“V”*. The standard unit of voltage is the **Volt**, also denoted by *“V”*.

To make it simpler take an example

- We have a table and two person pushing it in
**opposite direction**with**same forces**, for example**“F**so net potential difference (F_{A}=5 N& F_{B}=5 N”_{A }– F_{B}) is “**0 N”**so the table don’t move in any direction, where N is Newton unit of force - We have a table and two person pushing it in
**opposite direction**with**different forces**, for example**“F**so net potential difference (F_{A}=7 N& F_{B}=5 N”_{A }– F_{B}) is**“2 N”**so the table will move in one direction (because A have more force, table will move in direction in which A is pushing/pulling), where N is Newton unit of force

- We have a table and one person pushing and one person is pulling it in
**same direction**with**some forces**(either same or different forces),for example**“F**so net potential difference (F_{A}=5 N & F_{B}=4 N”_{A}+ F_{B}) is**“9 N”**so the table will move in direction of pushing/pulling with force of**“9 N”**, where N is Newton unit of force

**Conclusion: **More the potential difference faster the table (electrons) move.

__NOTE__*: **To drive a circuit both current and Voltage are essentially required.*

**COMMON RELATION BETWEEN VOLTAGE AND CURRENT**

**V = IR**

This formula is derived by German physicist Georg **Ohm**

**Ohm’s law** states that the __current__ through a __conductor__ between two points is directly __proportional__ to the __voltage__ across the two points. Introducing the constant of proportionality, the __resistance__, one arrives at the usual mathematical equation that describes this relationship

**I ****∝**** V**

**I = V / R**

Where *I* is the current through the conductor in units of __amperes__, *V* is the voltage measured *across* the conductor in units of __volts__, and *R* is the __resistance__ of the conductor in units of __ohms__. Ohm’s law states that the *R* in this relation is constant, independent of the current.

As

**R = V / I**

If current is 0 it makes resistance infinite, means in open circuit (current = 0) resistance is infinite no matter how much voltage is present.

## HOW ELECTRONS FLOW IN A CIRCUIT

First let us remember the basic concept of a **magnet** we all know, magnet has **two poles** one is the **North Pole** and other is the **South Pole**. “**Like** (same) magnetic pole” **repel** each other and “**unlike** (not same) magnetic poles” **attract** each other i.e. “North & South” (opposite) attract each other while “North & North or South & South” repel each other.

Same the concept above, electrons are negatively charged and many electrons push one electron (because same charge repel each other) then another electron then another electron this chain continues and electron emits from the source come back to the source if circuit is closed this process cause to flow current (electric charge) in a circuit.

*Electrons flow** from the negative terminal to the positive. Current flows from the positive terminal to the negative (conventionally).*

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