Alternative Media for Animation Longitudinal and Transverse Waves: A Brief Introduction

This document is the alternative media description for the animation “Waves on a Stretched Spring.” It provides a complete textual equivalent of the animation, combining instructional narration with descriptive audio. This document is intended for screen readers, e‑readers, and learners who cannot access visual media.

Overview

The animation demonstrates how waves move through a stretched spring. The spring itself does not travel across the screen as two pulses move along it. Instead, a disturbance moves along the spring, carrying energy from left to right.

A long metal coil spring is stretched horizontally. Only the left end of the spring is visible; the rest of the spring extends off to the right. A left hand grips the leftmost coil and holds the spring under tension, keeping it straight and horizontal.

Longitudinal Wave

The hand begins moving back and forth horizontally, along the same direction as the length of the spring. As the hand moves, some coils are pushed closer together, forming regions of compression. Between these regions, the coils spread farther apart.

These alternating compressions and expansions travel along the spring toward the right, moving away from the hand. Each individual coil moves back and forth about its equilibrium position, but does not travel along the length of the spring.

This type of motion is called a longitudinal wave, also known as a compression wave. In a longitudinal wave, the direction of the disturbance — here, the horizontal motion of the coils — is the same as the direction the wave travels, which is also horizontal.

The hand then stops its horizontal motion. The spring briefly returns to its evenly spaced, straight shape.

Transverse Wave

Next, the hand begins moving up and down vertically, perpendicular to the length of the spring. As the hand moves, each coil is displaced upward and then downward about its equilibrium position.

A rippling shape forms along the spring. This wave shape travels to the right, away from the hand. Even though the wave moves horizontally, each individual coil moves only up and down.

This type of motion is called a transverse wave. In a transverse wave, the direction of the disturbance — in this case, vertical motion — is perpendicular to the direction the wave travels, which remains horizontal.

Summary and Pulse Examples

This animation shows two types of wave disturbances. The disturbances move through the medium, while the individual parts of the medium move about their equilibrium positions without any bulk motion.

A single longitudinal pulse passes by, appearing as a brief compression followed by expansion moving through the medium.

Next, a single transverse pulse passes by, with the medium moving up and down as the disturbance travels forward.

In general, waves carry energy through a medium without transporting the medium itself.