Waves

WavesA wave is a disturbance that carries energy through matter or space.

It does not move matter.

Energy may spread out as a wave travels.

Types of WavesMechanical Waves – waves that require a medium

A medium is a material that the wave moves through.

Stone thrown in a pond

Sound from a stereo

Earthquake

Types of WavesElectromagnetic Waves – waves that do not require a medium

Light through space

Radio waves

Radar

Transverse & Longitudinal Waves

Transverse waves – waves in which the motion of the particles is perpendicular to the motion of the wave.

Waves in a rope

Longitudinal waves – waves in which the motion of particles is parallel to the direction of the wave

Sound waves Simulation

Characteristics of WavesWavelength – the distance between two similar points on a wave

Characteristics of WavesAmplitude – measured the amount of particle vibration or the height of the wave – half the height of the wave.

Characteristics of WavesFrequency – measures the rate of vibrations

As frequency increases the wavelength decreases.

Electromagnetic SpectrumThe electromagnetic spectrum

shows all the different types of electromagnetic waves (transverse).

The higher the frequency, the more energy it has.

They all travel at the speed of light.

Electromagnetic Spectrum

Wave SpeedThe speed of a wave depends on the material it is passing through.

The denser the material, the faster a mechanical wave will move through it (sound travels 3 – 4 times faster through water than air)

Example: Door, Train Tracks

A dense material will slow down an electromagnetic wave (light travels slower through glass than air)

Wave SpeedMechanical waves travel fastest through solids and slowest through gasses.

Transverse waves travel fastest through gasses and slowest through solids.

Doppler EffectThe Doppler effect is a change in the observed frequency of a wave resulting from the motion of the source or observerWaves are compressed as the sound source comes toward you producing a higher pitched sound. When it travels away the waves are farther apart producing a lower pitched soundThis occurs in both sound and light.

Doppler Applet

Characteristics of WavesHigher the frequency the greater the energy.

Lower the frequency the lower the energy.

Human hearing: 20 Hz to 20,000 HzDog hearing: 40 Hz to 46,000 Hz