Changing Mediums Tiffany Rhodes Cp1 Physics Chapter 11

Upon reaching the boundary, two behaviors will occur. (incident pulse - created by source) 1. reflected pulse - bounces off barrier and returns to source 2. transmitted pulse - continues on into next medium.

Case #1: Going from a less dense medium to a more dense medium Less to more dense ex. Changing from air to glass Changing from air to water Changing from water to concrete

Going from less to more dense, the barrier acts like a a fixed end scenario. What do you already know about the reflected pulse? Frequency? Wavelength? Speed? Amplitude? What do you think is going to happen to the transmitted pulse? Frequency? Wavelength? Speed? Amplitude?

Reflected Pulse: Frequency - same as incident Wavelength - same as incident Speed - same as incident (same medium) Amplitude - smaller than incident (lost energy) INVERTED (opposite side as incident)

Transmitted Pulse: Frequency - same as incident Wavelength - smaller than incident Speed - slower than incident (more dense medium) Amplitude - smaller than incident (more dense medium/ lost energy)

Check Out Animation

Case #2: Going from a more dense medium to a less dense medium More to less dense ex. Changing from glass to air Changing from water to air Changing from concrete to water

Going from more to less dense, the barrier acts like a a free end scenario. What do you already know about the reflected pulse? Frequency? Wavelength? Speed? Amplitude? What do you think is going to happen to the transmitted pulse? Frequency? Wavelength? Speed? Amplitude? More denseless dense

Reflected Pulse: Frequency - same as incident Wavelength - same as incident Speed - same as incident (same medium) Amplitude - smaller than incident (lost energy) UPRIGHT (same side as incident) More denseless dense

Transmitted Pulse: Frequency - same as incident Wavelength - bigger than incident Speed - faster than incident Amplitude - bigger than incident (less dense and more elastic despite loss of energy) More denseless dense

The boundary behavior of waves can be summarized by the following 5 principles: 1. the wave speed is always greatest in the least dense medium 2. the wavelength is always greatest in the least dense medium 3. the frequency of a wave is not altered by crossing a boundary

4.the reflected pulse either becomes inverted when hitting a more dense medium(fixed end) or upright when hitting a less dense medium (free-end) 5. the amplitude of the incident pulse is always greater than the amplitude of the reflected pulse.

Case 1: A pulse in a less dense medium is traveling towards the boundary with a more dense medium. 1. The reflected pulse in medium 2 ________ (will, will not) be inverted because _____________(acts like a fixed or free end). 2. The speed of the transmitted pulse will be ___________ (greater than, less than, the same as) the speed of the incident pulse. 3. The speed of the reflected pulse will be ______________ (greater than, less than, the same as) the speed of the incident pulse. 4. The wavelength of the transmitted pulse will be ___________ (greater than, less than, the same as) the wavelength of the incident pulse. 5. The frequency of the transmitted pulse will be ___________ (greater than, less than, the same as) the frequency of the incident pulse.

1.Will be – acts like a fixed end reflection. 2. Less than. 3. The same as. 4. Less than. 5. The same as

Check Your Understanding Case 2: A pulse in a more dense medium is traveling towards the boundary with a less dense medium. 1. The reflected pulse in medium 1 ________ (will, will not) be inverted because _______ (acts like a free or fixed end). 2. The speed of the transmitted pulse will be ___________ (greater than, less than, the same as) the speed of the incident pulse. 3. The speed of the reflected pulse will be ______________ (greater than, less than, the same as) the speed of the incident pulse. 4. The wavelength of the transmitted pulse will be ___________ (greater than, less than, the same as) the wavelength of the incident pulse. 5. The frequency of the transmitted pulse will be ___________ (greater than, less than, the same as) the frequency of the incident pulse.

1. Will not…acts like a free-end reflection 2. Faster 3. The same as 4. Greater than 5. Same as

Lets go out in the hall and see the demonstration of these 2 scenarios. Homework: Complete worksheet Study notes!!!