Waves in our world Part 1- Longitudinal and Transverse Waves and

communication

What is this topic all about???

The World Communicates

The Nature ofWaves

Properties ofSound Waves

Reflection&

Refraction

Digital Communication

& Data Storage

Electromagnetic Waves

General Types of Waves

• mechanical

•EM waves

•Transverse

•longitudinal

Wave Measurement

s

• wavelength

• amplitude

• frequency

•period

Wave Equatio

n

v = ƒ

Graphing Waves

Nature of Sound Waves

Velocity

Frequency & Pitch

Amplitude & Loudness

Principle of Superposition

The Electromagneti

c Spectrum

Production & Detection

of EMR

Dangers of EMRInverse

Square Law

EMR in Communicatio

nRefraction

Snell’s Law

Total internal reflection & critical angle

Law of Reflection

Reflection in communication

Light & Mirrors

2

1I

d

Waves in our World 1) A wave is a means of transferring energy and information from one point to another.

http://alex.state.al.us/lesson_view.php?id=24112

Waves in our World There is no transfer of matter between the two points. (means energy moves from one point to another. The particles in the wave do not move from one point to another).

Waves in our World

2) There are two types of waves:Transverse waves Longitudinal waves

Waves in our World

2) There are two types of waves:Transverse waves Longitudinal waves

Waves in our World How are Longitudinal waves different from transverse waves? 1) Longitudinal wave: is a wave whose particles oscillate in the same direction as the wave

2) Transverse wave: A wave whose particles oscillate perpendicular to the direction that the wave travels. travels.

1) Longitudinal wavesLongitudinal waves are waves where the vibrations of the particles are along the direction in which the wave travels.

example: sound waves, ultrasound

wave direction

vibrations

LONGITUDINAL WAVE

longitudinal wave in slinky

https://www.youtube.com/watch?v=y7qS6SyyrFU

Waves in our World

Waves in our World

2) Transverse wavesTransverse waves are waves where the direction of vibrations is at 90° to the direction in which the wave travels.

example: water waves

wave direction

vibrations

TRANSVERSE WAVE

1. The wave model can be used to explain how current technologies transfer information • describe waves as a transfer of energy disturbance that may occur in one, two or three dimensions, depending on the nature of the wave and the medium Waves carry energy from one place to another. All forms of wave motion transport energy, without transporting matter.

This may occur in 1 dimension (pulses moving along a slinky spring), 2 dimensions (ripples spreading out on a surface of water) and 3 dimensions (light radiating out from a light bulb).

• identify that mechanical waves require a medium for propagation while electromagnetic waves do not

Mechanical waves are those which require a medium to travel through. Sound waves need a substance such as air to travel through due to vibration of particles. Sound will not travel through a vacuum. “In space no one can hear you scream”.

Electromagnetic (EM) waves do not need a medium. They can travel through a vacuum and in fact travel fastest through empty space. EM waves are self propagating. (They will be looked at in more detail in later topics). EM waves include light, radio waves and X-rays.

• define and apply the following terms to the wave model: medium, displacement, amplitude, period, compression, rarefaction, crest, trough, transverse waves, longitudinal waves, frequency, wavelength, velocity

• describe the relationship between particle motion and the direction of energy propagation in transverse and longitudinal waves

There are two main types of mechanical waves; transverse and longitudinal (or compression).

• In a longitudinal wave, the vibration of the particles of the medium is along the same direction as the motion of the wave.

• With a transverse wave, the particles vibrate up and down in a direction perpendicular to the motion of the wave itself.

longitudinal wave transverse wave

Measuring Waves

• A transverse wave consists of a crest above the rest axis, and a trough below it.

• A longitudinal wave consists of compressions, where the particles are close together, and rarefactions, where the particles are spread apart.

• The amplitude (A) for both is the maximum displacement from the rest position. (Measured in metres)

• The wavelength () is the distance between any two consecutive points. (Measured in metres)

• The frequency () of a wave is the number of waves that pass a particular point in one second. Units are Hertz (Hz).

• The period (T) of a wave is the time it takes for one complete wave to pass a point. Units are seconds (s)

• quantify the relationship between velocity, frequency and wavelength for a wave:

v = ƒ • solve problems and analyse information by applying the mathematical model of v = ƒ to a range of situations

The wave equation indicates the speed of a wave in terms of wavelength and frequency.

v = ƒ

The units of velocity are ms-1

• perform a first-hand investigation to observe and gather information about the transmission of waves in:

– slinky springs– water surfaces

– ropes or use appropriate computer simulations

• present diagrammatic information about transverse and longitudinal waves, direction of particle movement and the direction of propagation

• perform a first-hand investigation to gather information about the frequency and amplitude of waves using an oscilloscope or electronic data-logging equipment

• present and analyse information from displacement-time graphs for transverse wave motionplan, choose equipment for and perform a first-hand investigation to gather information to identify the relationship between the frequency and wavelength of a sound wave travelling at a constant velocity