Physics / core

Wave Speed

Also known as: v

definition

The speed at which a wave pattern propagates through a medium, determined by the medium's properties. Why thunder arrives after lightning; why we see distant events before hearing them.

This concept is covered in depth in our wave speed and wavelength guide, with worked examples, practice problems, and common mistakes.

💡 Intuition

How fast the wave's shape moves forward through whatever it's traveling in.

Core Idea

Wave speed is determined by the medium it travels through, not by its frequency or source.

Formal View

For any periodic wave, the phase velocity is v = f\lambda = \lambda / T, where the speed depends solely on the properties of the medium (e.g., tension and density for a string, temperature for sound in air).

🔬 Example

Sound in air: ~343 \text{ m/s}. Light in vacuum: 3 \times 10^8 \text{ m/s}. Both are set by the medium.

🎯 Why It Matters

Why thunder arrives after lightning; why we see distant events before hearing them.

⚠️ Common Confusion

Wave speed is fixed by the medium—changing frequency changes wavelength, not speed.

💭 Hint When Stuck

When solving a wave speed problem, identify the frequency f and wavelength \lambda from the question. Then substitute into v = f\lambda and compute. If given period T instead of frequency, first convert using f = 1/T before applying the wave equation.

Related Concepts

Prerequisites

How Wave Speed Connects to Other Ideas

To understand wave speed, you should first be comfortable with wavelength and frequency.

Learn More

Go Deeper

Want the Full Guide?

This concept is explained step by step in our complete guide:

Forces, Motion, and Energy: A Concept Bridge Guide →

Frequently Asked Questions

What is Wave Speed in Physics?

The speed at which a wave pattern propagates through a medium, determined by the medium's properties.

Why is Wave Speed important?

Why thunder arrives after lightning; why we see distant events before hearing them.

What do students usually get wrong about Wave Speed?

Wave speed is fixed by the medium—changing frequency changes wavelength, not speed.

What should I learn before Wave Speed?

Before studying Wave Speed, you should understand: wavelength, frequency.

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