-Standing Waves -Law of Reflection -Diffraction -Interference of Waves Physics Mrs. Coyle
Standing Wave
Standing Waves Nodes: zero displacement Antinodes: maximum displacement
Forming a Standing Wave on a Rope Incident pulse interferes with the reflected (inverted) pulse.
How is a standing wave formed? Incident pulse Reflected pulse Standing wave
Wave on a String (Applet) string/wave-on-a-string_en.html string/wave-on-a-string_en.html
Standing Waves Applet /simulations6e/index.htm?newwindow=truehttp://www3.interscience.wiley.com:8100/legacy/college/halliday/ /simulations6e/index.htm?newwindow=true
L= 1/2 λ L= λ L= 1 1/2 λ L= 2 λ L=2 1/2 λ L=3 λ
Natural Frequencies of a Stretched String (Fixed Ends) Fundamental Frequency First Harmonic
Problem A string of length 1m vibrates. The speed of the wave in the material is 400m/s. Calculate the first three natural frequencies and draw the corresponding standing waves. Answer: 200Hz, 400Hz, 600Hz
Law of Reflection The angle of incidence equals the angle of reflection.
Refraction When a wave crosses a boundary between two different media, the wave changes direction because it changes velocity. Frequency is constant (as emitted from source) Velocity change is a result of wavelength change
Refraction
Why do ocean waves approach the beach parallel to the shore? Where is the speed greater? Hint: check the wavelength
Diffraction The bending of waves around a small obstacle or hole. The smaller the wavelength the smaller the diffraction.
One Wave Two Waves Interfering