Waves

Two Types Longitudinal Energy moves in the same direction of travel Transverse Energy moves perpendicular to the direction of travel

Parts of a Wave Crest Wavelength High point in a wave Trough Low point in a wave Node Points of no displacement Amplitude The height of the wave Wavelength the distance from one crest to the next crest Frequency The rate the crests pass a given point

Medium Matter (material) for waves to move through Mechanical waves require a medium Electromagnetic waves do not require a medium Dense mediums allow waves to move more quickly

Propagation of Waves Except for surface waves, waves propagate outward spherically in 3D - like the layers of an onion. The layers of an onion, are a good representation of how waves look as they travel- In every direction equally at the same time!

If the Wave propagated out on a separate 2D plane, I wouldn’t see it. Wave hitting my eye – I can see it! If waves propagated in only 2D like waves on a pond, then if we moved the candle up a little higher we wouldn’t be able to see it.

Longitudinal Wave Examples Sound waves Seismic P waves

Transverse Waves Examples Light Seismic S waves Vibrations in strings

Sound Pitch How high or low the sound is Depends on Frequency Volume How loud or quiet the sound is Depends on Amplitude

Energy Frequency How is energy related to: Amplitude? They are directly proportional: Increase Frequency = Increase Energy Increase Amplitude = Increase Energy Amplitude

Interference- when waves interact with each other Reflection A change in direction of waves when they bounce off a barrier Refraction A change in the direction of waves as they pass from one medium to another Diffraction a change in direction of waves as they pass through an opening or around a barrier in their path

Electromagnetic Waves

How do we know light travels in waves?  "Is light a wave or a stream of particles?“ Light exhibits certain behaviors characteristic of waves: Refraction, Diffraction and Reflection Interference Doppler Effect

Properties of Light Light waves do not need a medium the same way sound does Light is a wave of energy Each wave is made up of a photon of light A photon is a “bundle” of energy This bundle of energy excites other charged particles because of its charged properties This is why light makes things feel warm

Light Frequency = Type of light and color Our eyes are sensitive to light energy.  We perceive a low frequency light as red or yellow and a high frequency as blue or violet.

White Light Makes Vision Possible White Light is actually made up of ALL the different colors – each color is made up of its own frequency and wavelength.

Color When we look at something, we see the color that is reflected. For example, something red looks red because it is absorbing all of the other colors and reflecting the red wavelength. Reflected Incident Beam

Color What color would something be if it reflects all wavelengths? What color would something be if it absorbs all wavelengths?