SPH 3U1

Unit 4: Waves and Sound

Note 1: Introduction to Waves

Reference: Chapter 8.1, 8.2, 8.3

Demo: Bell Wave Machine
Applet:  http://www.ndt-ed.org/EducationResources/CommunityCollege/Ultrasonics/Physics/wavepropagation.htm

Definition of a Wave:

A wave is a transfer of energy over a distance caused by a vibrating source.

A wave moves through a medium or space.

A wave cannot transfer matter (when a wave moves through a medium, particles of the medium are displaced but return to their original position after the wave has passed...energy is transferred, not matter)

Transverse Wave:

- Has crests and troughs

- Motion of wave is perpendicular to motion of particles

- Example:water waves

Longitudinal Wave:

- Has rarefactions and compressions

- Motion of particles parallel to motion of particles

- Example:sound waves

Wave Terminology (Geometric):

- With the use of a diagram show crest, trough, amplitude, wavelength,

- Phase, Phase-Shift .....Students draw waves with a reference wave, 1/2 wavelength shift, 1/4 wavelength shift, one wavelength shift

- Discuss 'in phase' and 'out of phase'

Wave Terminology (Time Based):

Period (show on diagram), frequency

Simple Harmonic Motion (SHM):

- Motion that repeats itself (periodic motion) around an equilibrium point.

- Amplitude, period and frequency remain constant.

- i.e. pendulum, ideal spring-mass system.

Universal Wave Equation:

Interference:

When two waves interact, they are said to interfere with each other.

Principle of Superposition:

When two or more waves combine to produce a single wave. The resulting amplitude is the sum of the amplitudes of the individual waves.

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