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Year 8 Science Physical Sciences AC9S8P01

Sound & Wave Properties

Sound waves are longitudinal mechanical waves. Understanding wave properties explains how sound behaves in different environments.

What You Need to Know

Key Concept Diagram

Waves transfer energy without transferring matter

Longitudinal waves: particles vibrate parallel to wave direction (compression and rarefaction)

Wave equation: speed = frequency × wavelength (v = fλ)

Sound is reflected (echo), absorbed, or transmitted depending on the material

Key Vocabulary

Wavelength

The distance between two consecutive identical points on a wave

Compression

Region of a longitudinal wave where particles are pushed together

Rarefaction

Region of a longitudinal wave where particles are spread apart

Decibel

Unit used to measure sound intensity (loudness)

Knowledge Check

Select the correct answer for each question. Click "Check Answer" to see if you are right.

Question 1

A sound wave has a frequency of 340 Hz and a wavelength of 1 m. What is its speed?

Question 2

In a longitudinal wave, how do particles move relative to the wave direction?

Question 3

An echo is caused by:

Key Concepts Summary