Physics · KS3 Y7 · Waves (Light & Sound)

Sound needs a medium

Sound needs a mediumFree2:36Heddy Score 3 of 7, below the standard
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What you need to know

  • Sound is a longitudinal wave made of compressions and rarefactions.
  • Sound needs particles to pass on vibrations, so it cannot travel through a vacuum.
  • Sound changes speed in different media, while its frequency stays the same at a boundary.

In this clip

Runs 2:36, from 0:16 to 2:52 of the full video.

Also coversPitch and frequency
Heddy Score3/7, Below the standard
See the seven stars
  • Trusted source · passed. The creator's own upload, live and playable here.
  • On the map · not judged yet. A teacher watched it: it mainly teaches this map topic.
  • Spec-true · not judged yet. Accurate, and right for the current UK specification.
  • Focused · passed. One idea, short enough to watch in one go.
  • Accessible · passed. Good captions, clear sound and pictures.
  • Safe for children · not judged yet. Right for 11 to 16 year olds, with no sales pitch.
  • Proven · not judged yet. Earned from our students: they learn from it, find it helpful and watch it to the end.
★ passed · ☆ pending · ✕ failed
Our students

Not enough students yet

Our own students' answers. These are what move ★7 Proven.
On YouTube

574K views · 7.6K likes · Cognito 1.37M subscribers

As reported by YouTube on 2026-11-02. Not part of the Heddy Score.
How the Heddy Score works

Why we picked it

The first section explains sound transmission and the second traces how the ear detects it.

Cognito on YouTubechecked 2026-10-20

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