weekly post

waves. i am understanding waves quite well. Mr. Wirth, job teaching about waves.

sound waves are longitudonal waves

lkjs

the reflected pulse has a smaller amplitude than the incident pulse

Midterm Blog

I thought the mid term was alright. The multiple choice was a little hard and I thought that the writing portion was on the easier side.

2/6/08 Blog Post

Resonance: from L. Resonantia "echo"

the state of a system in which an abnormally large vibration is produced in response to an external stimulus, occurring when the frequency of the stimulus is the same, or nearly the same, as the natural vibration frequency of the system.

Class 2/4: Waves

In class we went over path difference, interference patterns, and briefly touched on nodes and anti-nodes. Path difference is interference between multiple waves. This occurs due to a difference in the length of the path the waves are traveling. Path difference can either cause constructive interference, when either a peak and a peak meet to create a higher peak or a tough and a trough meet to create a deeper trough, or destructive interference, when the waves are out of phase and cancel eachother out (a peak and a trough combining to cancel eachother out, forming a flat surface). Maximum constructive interference occurs when the path difference is an even number of half wavelengths and maximum destructive interference applies for an odd number of wavelengths. Next, we went over interference patterns. These are symmetrical patterns which occur when sources in the same medium are in phase. The examples given were a puddle of oil in a parking lot appearing rainbow-colored, the feathers on the head of a mallard, and mother of pearl. Nodes are where there is no displacement or amplitude, producing a "smooth area". This is because destructive interference cancels a peak and trough out. Anti-nodes are the oppostive, areas of maximum displacement produced by contstructive interference.

On Thursday we took notes on the Doppler Effect. In this picture we see the Doppler effect at work. When the car approaches with its siren blasting, the siren is high pitched because of its high frequency and the sound waves are closer together. After the car passes by, the siren is a lower pitch because of low frequency and the waves are spread further apart. The Doppler effect is how the sound waves shift in frequency when +produced by a moving source.

Approaching-Higher Frequency

-Higher Pitch

Receding-Lower Frequency

-Lower Pitch

WAVES!

DOPPLER EFFECT is a variation in observed frequency when there is relative motion between a source and an observer. Exampes: the pitch of the sound changing. The closer you are to the sound, the higher the pitch will be. The farther away you are, the lower the pitch will be. It's same with color. The farther away you are the dimmer the light is, and the closer you ar, the brighter it will be. The stars shifted towards us is blue while the stars shifted away from us is red is an example of the Doppler Effect.

Interference occurs when two or more waves pass simultaneously through a region. (look at picture A & B about waves interference) waves interference results in a new wave pattern. examples: boat waves, sound waves. Interferences produces beats which is like the spokey or "shuddery" noise when mr. wirth hit those two tone forks. LAW OF SUPERPOSITION- when waves overlap each other. the resultant displacement is the algebraic sum of the individual displacements of each wave. annull = cancel out CONSTRUCTIVE INTERFERENCE- occurs wehn we have two waves arriving at the same point are vibrating in the same direction (in phase). THe two waves are added together to form a bigger. PEAK + PEAK = BIG PEAK & TROUGH + TROUGH = BIG TROUGH

MAXIMUM CONSTRUCTIVE INTERFERNECE- occurs when the phase difference is zero degrees (in phase).
DESTRUCTIVE INTERFERENCE- occurs when 2 waves arriving at the same point are vibrating in opposite directions (out of phase) . waves cancel one another out. PEAK + TROUGH= ZERO.
MAXIMUM DESTRUCTIVE INTERFERENCE- occurs when the phase difference is 180 degrees and its "out of phase".
look at picture for constructive and destructive interference
PATH DIFFERENCE- is the interference between 2 waves of ten occurs due to a difference in length of the path that 2 waves travel.