Waves Introduction

Chapter 10 Section 1 and 2

Physics Standard 4

Physics

Science that deals with

matter, energy and

their interactions

Definition• Wave: disturbance that carries

energy through matter or space.

• Matter through which a wave travels is called its medium.

• Waves transfer energy and energy spreads out at it travels.

Medium Examples

What is the Medium?

What is the Medium?

Water

Air

Mechanical vs. Electromagnetic

• Mechanical waves: require a medium to travel through. Ex: Sound

• Electromagnetic waves: do not require a medium. Ex. light

Mechanical Types

• 1) Transverse: causes particles of medium to vibrate perpendicularly to direction wave travels.

• Ex: water• http://www.acoustics.salford.ac.uk/feschools/waves/flash/transverse.swf

Transverse Wave

Transverse Wave

• Crest: highest pt• Trough: lowest pt• Amplitude: greatest

distance that particles in medium move when a wave passes.

• Wavelength: dist. from 1 crest of wave to next crest.

• Frequency: # of full wavelengths that pass a point in a given time.

Characteristics of a Transverse Wave

Rules• Higher amplitude + Short wavelength

wave carries much energy.• Low amplitude + long wavelength

wave carries little energy.

Which One Carries More Energy?

Mechanical Types

• 2) Longitudinal: causes particles of medium to vibrate parallel to direction the wave travels. Ex: sound

Longitudinal Wave Characteristics

• Compression: area where particles are close together.

• Rarefaction: area where particles are spread out.

Sound: Longitudinal Wave

• Sound wave speed depends on medium it is in.

• Sound in air: 340 m/s

• Sound in water: 3 x’s faster than in air.

• Sound in solid: 15-20 x’s faster than in air.