Crave the Wave

In Crave The Wave, participants will demonstrate knowledge and process skills needed to solve problems and answer questions regarding all types and areas of waves and wave motion. A calculator is required for this event.

2009
Note that for 2009 there are no regional, state, and national topics, as these topic categories refer to last year's. You are required to know all of the topics for every level of competition.

Regionals Topics

 * General Wave characteristics- Wavelength, amplitude, frequency, period.
 * Wave Types- Transverse, longitudinal, surface, torsional waves.
 * Wave Phenomenon- Sound and Light, reflection, standing waves, constructive and destructive interference, refraction, effect of media diffraction, Doppler effect.
 * Electromagnetic Waves- Electromagnetic spectrum, relationship between frequency and wavelength, energy carried (AM/FM only), standard wavelength bands, their uses and dangers. Others are about how the electromagnetic spectrum relates to everyday life and the knowledge of mechanical and electromagnetic waves.

Some calculations are required, such as calculation of frequency, period, wavelength, and speed.

Wave Characteristics
The main parts of a transverse wave are the crest, trough, wavelength, and amplitude. Also, there are additional characteristics of waves, such as frequency and period.


 * Crest- the highest point of a wave. Also called peak.
 * Trough- the lowest point of a wave.
 * Rest position- the vertical midpoint of a wave.
 * Wavelength- the distance between two crests or troughs.
 * Amplitude- the distance between a crest or trough and the rest position.
 * Frequency- the number of times a wavelength passes a point in one second.
 * Period- the time a wave takes to complete a wavelength.

Some of these parts are shown in the picture below:



Types of Waves
The 2 main types of waves are longitudinal and transverse. Transverse waves propagate at a 90$$^\circ$$ angle to the medium- they move up and down. Longitudinal waves move forwards and backwards. An example would be a slinky. Surface waves take place in water. They are called orbitals, and move in circles. Torsional waves twist and spin. It is like a screw being drilled, or moving your arms back and forth while keeping them flat.

State Topics
At States you will need to demonstrate your knowledge about spectroscopy, with topics such as absorption spectra, primary colors of pigments, and emission spectra. Seismic waves are also included.

Seismic Waves
There are 5 major earthquake waves:


 * P-waves- aka primary waves, are longitudinal waves. They are the first to arrive. They can travel through liquids.
 * S-waves- aka secondary or shear waves, are transverse waves. They are second to arrive. They cannot travel through liquids.
 * Surface Waves- combinations of P and S waves and occur on the surface. They are the slowest waves.
 * Rayleigh Waves- waves that roll in an ocean-like motion.
 * Love Waves- waves that move in side to side, horizontally. Love waves cause the most damage.

National Topics
In addition to the Regional and State topics Nationals will introduce Breaking ocean waves and Tsunamis.

Equations to Know
There are several helpful formulas and equations to know.
 * Frequency
 * Frequency=1/Period
 * Period
 * Period=1/Frequency
 * Speed
 * Speed=Distance/time
 * Snell's Law
 * $$\sin <I \cdot n_1=\sin <R\cdot n_2$$
 * Rayleigh criterion
 * Young's Equation
 * Gratings
 * Harmonics and Resonant Frequency
 * Polarization
 * Brewster's Angle
 * Energy of a Photon
 * Dimensional Analysis
 * Wavelength of Colors

Sample Questions
If the frequency is 2 Hz (2 cycles per second), what is the wavelength?

If the wavelength is 2 cm, what is the frequency in Hz (cycles per second)?

If the period is 2 seconds, what is the Frequency?

What is Destructive Interference?

Which seismic wave is faster? Primary waves or Secondary waves?

Given an image of a wave, identify the wavelength.

Sample Exercises
[[Media: 2008 Crave the Wave State Test.pdf|Crave the Wave State Test (2008)]]

[[Media: 2009 Crave the Wave Practice Test.pdf|Crave the Wave Test (2009)]]

[[Media: 2009 Crave the Wave Answers.pdf| Crave the Wave Test Answers (2009)]]

Websites and Resources
[[Media:Crave the Wave Resource Binder.pdf|A Crave the Wave Resource Binder (2007-2008)]]

http://www.glenbrook.k12.il.us/gbssci/phys/Class/waves/wavestoc.html

http://www.physicsclassroom.com/Class/waves/

http://www.physicsclassroom.com/Class/sound/

http://www.physicsclassroom.com/Class/light/

http://www.physicsclassroom.com/Class/refln/

http://www.physicsclassroom.com/Class/refrn/