Waves at boundaries (reflection and more)

Waves at boundaries (reflection and more) Fixed-end Animation A pulse reaching the end of a medium becomes inverted whenever it reflects off a fixed end.

Fixed end reflection

Waves at boundaries Reflection Free-end Animation a pulse reaching the end of a medium does not become inverted whenever it reflects off a free end.

Free end reflection

Waves at Boundaries (thinking not writing) Characteristics of a Transmitted Pulse A pulse (and a wave) carries energy through a medium from one location to another. But when the pulse reaches the end of the medium, where does the energy go? Does the energy disappear? Or does the energy pass into the new medium?

Waves at Boundaries Animation Rather than disappearing (and thus violating energy conservation), the energy carried to the boundary is divided up into a reflected pulse (which remains in the less dense medium) and a transmitted pulse (which passes across the boundary into the new medium).

From one medium to another. It takes more energy to move a more From one medium to another. *It takes more energy to move a more dense material. *Not all of the enrgy will get transferred. (think of echoes).

Waves at Boundaries In conclusion, the boundary behaviour of waves is best summarized by the following statements: the wave speed is always greatest in the least dense medium, the wavelength is always greatest in the least dense medium, the frequency of a wave is not altered by crossing a boundary,

the reflected pulse becomes inverted when a wave in a less dense medium is heading towards a boundary with a more dense medium, the amplitude of the incident pulse is always greater than the amplitude of the reflected pulse.

Superposition Interference of Waves

Superposition (Interference of waves) Constructive Interference

Interference of waves Destructive Interference

As the sine crests move towards each other, there will eventually be a moment in time when they are completely overlapped The individual sine crests are drawn in red and blue and the resulting displacement of the medium is drawn in green. Constructive or destructive?

Constructive or Destructive interference? Diagram A Diagram B

Standing Waves If periodic transverse waves travel in opposite directions on a spring, rope, or wave machine, a standing wave pattern can be set up. The pattern has supercrests, supertroughs, and nodes. The nodes stay standing in the same position. Standing waves produce the sound in wind instruments.

Make a table of terms; nodes antinodes standing wave natural frequency fundamental frequency

Review A standing wave is formed when a wave refracts due to changes in the properties of the medium. a wave reflects off a canyon wall and is heard shortly after it is formed. red, orange, and yellow wavelengths bend around suspended atmospheric particles. two identical waves moving different directions along the same medium interfere.

The number of nodes in the standing wave shown in the diagram at the right is 6 7 8 14

The number of antinodes in the standing wave shown in the diagram above right is 6 7 8 14

The number of nodes in the entire pattern is 7 8 9 16

Of all the labeled points, destructive interference occurs at point(s) B, C, and D A, E, and F A only C only all points