Wave Webquest Objectives: Students will gain a better understanding of the following What the different types of waves are Interference of two waves The reflection of waves on a spring The concept of standing waves Directions: Check out the links within each titled section, then answer the questions. More importantly, understand the answers to each question. (Let me know if there are any links that do not work.) Basic Wave Phenomena What is a Wave? - a disturbance which travels through a medium Longitudinal and Transverse Waves - Particle Motion for Longitudinal, Transverse, Water and Rayleigh Surface Waves Introduction to Waves Parts of a Wave - Shows the parts of a transverse wave. Frequency of Waves 1. What is a "wave"? What is necessary for a wave? How do particles within the medium travel? How do they NOT travel? 2. How are the particles moving relative to the direction the wave is traveling (direction of "propagation")? a) Longitudinal b) Transverse c) Water Waves. 3. What happens to the motion of the particles in a water wave, as the depth increases? 4. What are areas of "compression" and "rarefaction", and in which type of wave do they apply? 5. Using a diagram, label the parts of a transverse wave, including crest, trough, amplitude , phase, and the three ways to measure the wavelength. 6. Define the word "frequency". 7. What are "periodic waves"? 8. How does frequency apply to periodic waves? 9. How does increasing the wavelength affect the frequency? 10. How does increasing the wave speed affect the frequency? Reflection and Refraction Phase changes upon reflection from hard, soft, and mixed boundaries Compare the waves as the undergo reflection and refraction by completing the table: Situation Comparison Reflect from hard boundary Reflect from soft boundary Mixed boundary (low density or high density) Mixed boundary (high density to low density) Incident wave and reflected wave Incident wave and reflected wave Incident wave and reflected wave Incident wave and transmitted wave Incident wave and reflected wave Incident wave and transmitted wave Amplitude (larger, smaller, same size) Polarity (upright or inverted) Wavelength Speed (larger, smaller, same size) (faster, slower, same) Interference Superposition of Two Waves - Interference, Standing Waves, and Beats. Study these for a while, you may actually start to understand them! More Superposition - Control the speed and timing. Even More Wave Interference - Check out all of the crazy shaped waves colliding in this action packed site! Coupled Oscillators - energy transfer between two mass-spring systems coupled together 1. Do waves bounce off each other, or go through each other? Are they affected in any way after the "collision"? 2. Define the process of "superposition" of two transverse waves. 3. Explain why it was possible to hit the middle cup in the spring exercise, but not hit the outer two cups? 4. Explain what is happening when two sine waves with equal wavelengths, but different phases interfere with one another. (The second animation on the "Superposition of Two Waves" link.) Standing Waves Superposition of Two Waves (Check out the standing wave animation.) Excellent Standing Waves - It doesn't get any better. From Reflections Vibrational Modes of a Hanging Chain - mode shapes for a hanging chain Vibration of a Fixed-Fixed String - mode shapes, and frequency spectra for a plucked string Rectangular Membrane - and degenerate modes of a square membrane Circular Membrane - or how a drum head vibrates Vibration of Baseball Bats - bending modes (sweet spot) and cylinder modes (ping) Vibrational Modes of an Electric Guitar - actual experimental Modal Analysis data Vibrational Modes of an Acoustic Guitar - actual experimental Modal Analysis data Tacoma Narrows Bridge - when engineers don't account for resonance when designing structures 1. What is a standing wave? 2. Explain what is necessary for standing waves to occur. 3. What is a "node", in relation to a standing wave? Diffraction Wave Interference – set up simulations to represent diffraction 1. Run the wave interference simulation. Line up frequency and amplitude two-thirds of the way along the slider. In the water situation with one drip create two slits, less than 2.5 cm slit width, barrier located at 3.1 cm and a slit separation less than 4.2 cm. Run the simulation and then after a few seconds pause it. Draw a sketch of what you see. 2. Change from water to light waves and repeat the instructions above (one light-two slits). Does the diffraction pattern change for either water or light waves? 3. Reset the light waves simulation and show the screen and graph. Add a 2-slit barrier to the simulation and allow the graphs to be formed. Observe the interference pattern created when the characteristics of the simulation are adjusted. You may have to adjust amplitude when other elements of the simulation are changed to observe the graph. What effect do the following changes have on the diffraction pattern? a. Shorter wavelength b. larger barrier-to-screen distance c. smaller slit width d. smaller slit separation