Study Guides/Physics/Define Potential Difference
Study Guide · Physics

How to Define Potential Difference (Voltage)?

When you study electricity in physics, you constantly hear the word 'Voltage'. However, in strict scientific terms, Voltage is officially known as Electric Potential Difference.

Without Potential Difference, a battery is completely useless, and not a single electron will ever move through a wire.

Question (Click to Flip)

How do you define potential difference?

Answer

Potential difference is defined as the amount of work done in bringing a unit positive charge from one point to another in an electric circuit.

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Key Facts

Definition: The work done to move 1 Coulomb of charge from point A to point B.

Common Name: It is universally known as 'Voltage'.

SI Unit: Volt (V), named after Italian physicist Alessandro Volta.

Measuring Device: Voltmeter (Always connected in Parallel).

Formula: V = W / Q (Voltage = Work / Charge).

The Exact Scientific Definition

The Potential Difference between two points in an electric circuit is strictly defined as the amount of Work Done (energy used) to move a unit positive charge (1 Coulomb) from one point to the other.

  • Think of a copper wire like a horizontal pipe filled with water. The water will not flow unless you tilt the pipe. The 'tilt' or the 'pressure' that violently pushes the electrons forward through the wire is exactly what we call the Potential Difference.

The Mathematical Formula

The physics formula for Potential Difference is: V = W / Q

  • V = Potential Difference (Voltage)
  • W = Work Done (measured in Joules)
  • Q = Electric Charge moved (measured in Coulombs)

Therefore, if an AA battery does exactly 1 Joule of work to push 1 Coulomb of charge through a wire, the battery has a potential difference of exactly 1 Volt.

How is it Measured?

To measure the Potential Difference acting across a lightbulb, a scientist uses a device called a Voltmeter. A voltmeter must always be connected strictly in Parallel across the component, never in series, because it needs to measure the 'difference' in pressure between the starting point and the ending point.

Questions and Answers

How do you define potential difference?+

Potential difference is defined as the amount of work done in bringing a unit positive charge from one point to another in an electric circuit.

What is the SI unit of potential difference?+

The official SI unit of potential difference is the Volt (V).

What is the difference between Voltage and Potential Difference?+

In basic electrical engineering, they are the exact same thing. 'Voltage' is simply the casual, everyday term used to describe the scientific concept of Potential Difference.

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