What is a wave?  A wave is a transfer of energy from one point to another via a traveling disturbance  A wave is characterized by its wavelength, frequency, and amplitude

Transverse  Waves that travel perpendicular to the direction of motion  Examples: Light, - p waves for earthquakes, Ocean waves

Longitudinal  Waves that travel parallel to the direction of motion  Made up of compressions and rarefactions in the medium that they are traveling in  Examples: sound waves and s waves for earthquakes

Wavelength (λ)  Distance from successive crest to crest or trough to trough for a transverse wave. Distance between one compression to another compression or rarefaction to rarefaction in a longitudinal wave.  Measured in meters

Frequency  Number of crests passing by per second  Measured in Hertz (Hz) defined to be one cycle per sec  Equal to the inverse of the amount of time it takes one wavelength to pass by

Amplitude  Maximum displacement of the wave  The amplitude will have different units depending on the type of wave  In a sketch of the wave, it is the distance from the middle of the wave to the peak

Wave Speed Where, v is the speed of the wave (m/s) λ is the wavelength in meters (m) f is the frequency in Hertz (cycle/s) Traveling Waves move through space at a certain speed

Interference  There are two types of interferences when two waves are moving towards each other.  Constructi ve interference  Destructive interference

Constructive interference With constructive interference, two waves will combine to make one wave where the amplitude is a combination of the two waves.

Destructive interference  With destructive interference, the waves will cancel each other if they have the same amplitude.

 Use a wave demonstration kit for students to show transverse and longitudinal waves as well as the types of interferences

a. Reflection - the bouncing back of a wave. 1) Sound echoes 2) Light images in mirrors 3) Law of reflection i = r

Refraction - the bending of a wave caused by a change in speed as the wave moves from one medium to another.

The girl sees the boy’s foot closer to the surface than it actually is.

Diffraction - the bending of a wave around the edge of an object. 1) Water waves bending around islands 2) Water waves passing through a slit and spreading out

Diffraction depends on the size of the obstacle or opening compared to the wavelength of the wave. Less occurs if wavelength is smaller than the object. More occurs if wavelength is larger than the object.

Interference - two or more waves overlapping to form a new wave.

1) Constructive (in phase)-The amplitudes of the waves combine as the waves pass each other

2) Destructive (out of phase) Sound waves that destructively interfere are not as loud

Standing wave - a wave pattern that occurs when two waves equal in wavelength and frequency meet from opposite directions and continuously interfere with each other. node antinode

Resonance - the ability of an object to vibrate by absorbing energy at its natural frequency.

 1. What is the v if λ = 8 m and ƒ = 20 Hz?  2. What is the λ if v = 50 m/s and ƒ = 25 Hz?  3. What is the ƒ if v = 50 m/s and λ = 10 m?  4. What is the v if λ = 1 m and ƒ = 345 Hz?  5. What is the λ if v = 100 m/s and ƒ = 3 Hz?  6. What is the ƒ if v = 120 m/s and λ = 3 m?  7. What is the v if λ = 3 m and ƒ = 10 Hz?  8. What is the λ if v = 345 m/s and ƒ = 790 Hz?  9. What is the ƒ if v = 345 m/s and λ =.25 m?