Waves & Wave Properties Introduction to Wave Properties Unit 10 Waves & Wave Properties Introduction to Wave Properties

A wave is … …a motion of disturbance Waves “propagate in 3-dimensions”. Waves move through a medium – the particles do not MOVE WITH THE WAVE!

A wave moves through the medium A wave moves through the medium. The medium does not move WITH the wave motion. The particles in the medium vibrate! http://www.youtube.com/watch?v=bEfrtAOMuvk (1:26)

General Wave Form crest Equilibrium Line trough

There are 2 types of waves Transverse Wave Longitudinal Wave Particle vibration is parallel to wave motion Particle vibration is perpendicular to wave motion

Transverse Wave Particle vibration is perpendicular to wave motion

Slow Motion Video of “Transverse Wave” http://www.acoustics.salford.ac.uk/feschools/waves/bungyvideo.htm http://www.acoustics.salford.ac.uk/feschools/waves/guitarvideo.htm

Longitudinal Wave Particle vibration is parallel to wave motion

Slow Motion Video of “Longitudinal Wave” http://www.acoustics.salford.ac.uk/feschools/waves/slinkyvideo.htm

Label the following examples as transverse or longitudinal waves.

Waves move through the medium! vibrates The wave only __________________ the particle, the particle does not __________ with the wave. move

There are 2 Categories of Waves Mechanical Waves Electromagnetic Waves Need a medium to travel through. Can travel without a medium For example, through gas, liquid or solids For example, through a vacuum

And an example of a longitudinal wave! Sounds waves are… Mechanical waves! And an example of a longitudinal wave!

Electromagnetic Waves Light waves are Electromagnetic Waves And an example of a transverse wave.

Speed of light = frequency x wavelength Wave Speed Equation V=f λ velocity = frequency x wavelength c =f λ Speed of light = frequency x wavelength

v = 340 m/s c = 300,000,000m/s Sound needs a medium to travel Speed of Sound in standard air: Light can travel through a vacuum Speed of Light in a vacuum: v = 340 m/s c = 300,000,000m/s

Frequency, Wavelength & Speed

Which wave has the lower frequency? Which wave has the higher frequency? Which wave has the lower speed? Lower frequency Higher frequency Same Speed!

Which wave has the higher frequency Which wave has the higher frequency? Which wave has the higher wavelength? Which wave has the higher speed? higher frequency Same speed! higher wavelength

What is the relationship between speed, frequency and wavelength? The only way to change the speed of the wave is to _______________________. A change in the frequency will change _____________. A change in the wavelength will change ___________. To change the medium wavelength frequency

Interference “The Superposition Principal”

Show resultant wave and label each as constructive or destructive interference. Complete destructive interference Constructive interference Destructive interference

Which Wave is the Resultant Wave? This is the resultant wave!

Which Wave is the Resultant Wave?

Waves can “Reflect” Reflection occurs for both mechanical and electromagnetic waves. Sound and light waves can both reflect, but do so with various rules which will later be discussed with examples. Below are two common examples of sound and light reflecting. Sound waves can reflect causing what we know as an echo. Light waves can reflect causing what we know as a mirror effect.

Standing Waves A wave pattern that results when two waves of the same frequency, wavelength and amplitude travel in opposite directions and interfere.

Standing Waves have ‘nodes’ and ‘antinodes’ A point in a standing wave which has the maximum amplitude. Node: A point in a standing wave which has no amplitude.

How many nodes and antinodes are in each standing wave? Create a Standing Wave! 2 nodes, 1 antinode 3 nodes, 2 antinodes 4 nodes, 3 antinodes

The Doppler Effect An apparent change in frequency due to relative motion. Examples: Car music/horn as it drives by Police sirens Sonic Boom! (Breaking the sound barrier) Red shift and blue shift with light waves High frequency Low frequency http://youtu.be/h4OnBYrbCjY (0-1min)

The Doppler Effect Large apparent wavelength Low Frequency wave Small apparent wavelength High Frequency wave