Voltage, Current, and Power

What is Voltage: -

Definition

Voltage, also called electric potential difference, is the force or pressure that pushes electric charges through a conductor. It is the energy per unit charge required to move electrons from one point to another.

It is measured in volts (V).

Formula:

$$V = \frac{W}{Q}$$

Where:

• $V$ = Voltage (Volts)
• $W$ = Work done or energy (Joules)
• $Q$ = Electric charge (Coulombs)

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Analogy

Think of voltage like water pressure in a pipe. The higher the pressure (voltage), the more forcefully water (current) flows through the pipe (wire).

Types of Voltage

1. AC Voltage (Alternating Current) – Changes direction periodically (e.g., household power supply)

2. DC Voltage (Direct Current) – Flows in one direction only (e.g., batteries)

What is Current: -

Definition

Current is the rate of flow of electric charge in a circuit. It represents how many electrons are flowing through a conductor per second.

It is measured in amperes (A).

Formula:

$$I=\frac{\mathrm{Q/}}{t}$$

Where:

$I$

Analogy

If voltage is the pressure in a pipe, current is the amount of water flowing through it. More water flowing per second = higher current.

Types of Current

1. Direct Current (DC) – Constant direction of flow (e.g., USB charger)

2. Alternating Current (AC) – Periodic change in direction (e.g., mains electricity)

What is Electrical Power: -

Definition

Power is the rate at which electrical energy is transferred or converted. It tells us how quickly energy is being used or generated.

It is measured in watts (W).

Formula:

$$P=V\times I$$

Where:

• $P$ = Power (Watts)
• $V$ = Voltage (Volts)
• $I$ = Current (Amperes)

This is known as Joule’s Law in electricity.

Analogy

If voltage is water pressure and current is water flow, then power is how quickly the water wheel spins—how much work is being done.

The Bridge Between Voltage, Current, and Resistance: -

Ohm’s Law creates a bridge between voltage, current, and resistance.

Ohm’s Law is one of the most important relationships in electrical circuits. It links voltage, current, and resistance.

$$V=I\times R$$

Where:

$V$

From this equation, we can also derive:

• I = V/R
• R=V/I

Units and Symbols:-

Quantity	Symbol	Unit	Unit Symbol
Voltage	V	Volt	V
Current	I	Ampere	A
Power	P	Watt	W
Resistance	R	Ohm	Ω

Measuring Voltage, Current, and Power: -

Measuring Voltage

1. Measured using a voltmeter.
2. Connected in parallel across the component.

Measuring Current

1. Measured using an ammeter.
2. Connected in series with the circuit.

Measuring Power

1. Can be calculated using voltage and current readings.
2.  A wattmeter is used in AC systems.

Applications of Voltage, Current, and Power: -

Understanding V, I, and P is essential in the following areas:

1. Home Appliances

• Ensuring safe operation by matching ratings.
• Preventing overloads and short circuits.

2. Electronics

• Designing circuits with proper resistors and power ratings.
• Powering sensors, microcontrollers, and ICs.

3. Renewable Energy

• Solar panels: Voltage depends on sunlight; current determines output.
• Inverters convert DC to AC with precise power control.

4. Electric Vehicles

• Battery voltage (e.g., 400V) and motor current define power output and range.

5. Power Grids

• High voltage is used for transmission to reduce current and power loss.

Conclusion: -

Understanding voltage, present-day electricity, and electricity is fundamental in both theoretical and practical electrical engineering. Whether you’re troubleshooting an energy issue at home or designing a sophisticated digital circuit, those three concepts will guide your decisions.

They aren't just academic terms; they are sensible gear that helps us design, examine, and accurately control the electrical systems we rely on every day.