The Nature of

WavesPHYSICS 1

Forth and

BackVIBRATIONS AND WAVES

Vibration

Wiggles in TIME

Swings forth and back

By its nature, it wiggles

Galileo Galilei

Pisa Cathedral; chandelier

Isochronism of the pendulum

Length and Mass

Length affects the number of swings

Mass does not affect the number of swings

VIBRATIONS OF A PENDULUM

“The crests and troughs of the sea of life that flows”

PARTS OF A WAVE

WAVE DIAGRAM

Crest

Trough

Wave LengthAmplitude

Equilibrium

Crest

Highest point away from the equilibrium

Trough

Lowest point away from the equilibrium

Amplitude [ A ]

Size of the maximum disturbance away from the equilibrium

Distance from the equilibrium to the crest or trough

Wavelength [ λ ]

One cycle from the equilibrium

Distance between one full crest to one full trough

Minimum distance for a wave to repeat itself

Distance between two successive, identical parts of the wave

PARTS OF A WAVE

PERIOD AND FREQUENCY

Wave

Motion

PROPAGATION OF

WAVES

Mass and energy are

transferred

Energy is transferred but

not mass

A continuous production of

pulses creates a wave

ENERGY TRANSFER

1. A wave transfers energy

2. A wave does not transfer matter from one place to another

3. A wave transmits information

CHARACTERISTICS OF WAVES

-1.5

-1

-0.5

0

0.5

1

1.5

0

15

30

45

60

75

90

10

5

12

0

13

5

15

0

16

5

18

0

19

5

21

0

22

5

24

0

25

5

27

0

28

5

30

0

31

5

33

0

34

5

36

0

Mechanical Wave

Waves that need a medium

to travel

Electromagnetic Waves

Waves that do not need a

medium to travel

Medium

Material used for energy to

travel

Can be solid liquid or gas

TYPES OF WAVES

Longitudinal Waves

a wave who’s direction

of propagation is

parallel to the direction

of vibration

Transverse Waves

a wave who’s direction

of propagation is

perpendicular to the

direction of vibration

A longitudinal wave

can be represented as

a transverse wave and

vice versa

TYPES OF WAVES

Frequency

and

WavelengthWAVE SPEED

INTRODUCTION

WAVE EQUATION

In Phase

and Out of

PasePARTICLE MOVEMENT

Wave Motion

Transfer of energy from the source to a distant receiver without the

transfer of matter.

Precise Definition for Wavelength

A wavelength is the distance between two successive particles

vibrating in phase

Phase of the Wave

The motion, direction and position of a particle within the wave

sequence

DEFINITIONS

In Phase

Particles have the same displacement and are moving in the same

direction

Particles that are an integral number of wavelengths apart are

vibrating in phase

Out of Phase

Particles that have opposite displacement and are moving in

opposite directions

Particles in one wavelength have the same frequency and

amplitude but there is a phase lead from one particle to the

next

Particles that are a half of a wavelength or a half plus an

integral amount of wavelengths are exactly or totally out of

phase

PHASE