Waves

4 Types of Waves

• Transverse

• Longitudinal

• Circular

• Torsion

Transverse waves

A transverse wave is one in which the disturbance is perpendicular to the direction of travel of the wave.

Examples: Light wave, waves on a guitar string.

Longitudinal Waves

Longitudinal wave is one in which the disturbance is parallel to the line of travel of the wave.

Example: Sound wave in air is a longitudinal wave.

Circular Water WavesSometimes called Surface Water Waves

The motion of particles in

surface water waves are circular.

Circular Wave

Circular Wave

Torsion Waves

• Particles move in a twisting motion.

Torsion Waves

• Particles move in a twisting motion.

The Doppler Effect

Pitch sounds higher as truck gets closer to you. (shorter wavelength)

Truck sounds lower as truck moves away. (longer wavelength)

Doppler Effect

Doppler Effect

• http://www.acs.psu.edu/drussell/Demos/doppler/doppler.html

• http://www.absorblearning.com/media/attachment.action?quick=153&att=2947

Constructive Interference

Louder sound (amplify) when compressions interfere constructively.Light gets brighter (amplify) when crest interferes with crest

Destructive Interference

Compressions interfere with rarefactions to make sounds quieter.

Crests interfere with a trough to cancel or make a wave smaller.

Noise-canceling headphones utilize destructive interference

http://bcs.wiley.com/he-bcs/Books?action=mininav&bcsId=3138&itemId=0471663158&assetId=92188&resourceId=7923&newwindow=true

Reflection of Light

Law of Reflection - angle of incidence = angle of reflection.

Ex: If the angle of incidence is 90 degrees the angle of reflection is _______ degrees.

Reflection

Standing Wave

• Wave appears to be standing still because the wave is being reflected.

One Standing Wave

Resonance• An object vibrates

sympathetically and

amplifies the energy of the wave. Violin strings would be quiet without the

resonance (amplification) of the violin’s body.

• Some said the Tacoma Narrows Bridge fell due to the resonance with the wind.

• http://www.youtube.com/watch?v=j-zczJXSxnw

Natural Frequency & Resonance

• Natural Frequency – frequency of an object when disturbed

• Resonance – objects ability to vibrate by absorbing energy at its natural frequency

Diffraction

Diffraction – waves bend around an object

Waves bend more if the object is smaller than the wavelength.

Diffraction of Sound

Refraction

• When light enters a new medium it changes speed and bends.

• Example: White light in air goes through a prism (glass) causing the white light to refract (bend) and spread out.

• http://www.youtube.com/watch?

v=GKoMSvmM-s8 Polyanna

demonstrating refraction (1:10 to 1:13)

Refraction

Refraction and Speed of the Wave

The Electromagnetic SpectrumRadio waves, Microwaves, Infrared waves, Visible Light, Ultraviolet Rays, X-Rays, Gamma

Rays

fv Visible Light –Remember ROY G BIV

Red, Orange, Yellow, Green, Blue, Indigo and Violet

Long Wavelength

Low Frequency

Low Energy

Short Wavelength

High Frequency

High Energy

Infrared Rays

Visible Light

Ultraviolet Rays

X-Rays

Convex Lens Also called a converging lens and is thicker in the middle. It makes light converge or meet at a focal point.

Concave Lens

• Also called a diverging lens, looks like it is caving in. It causes light to spread out.