Waves Vocabulary words are in red

Mechanical Wave A disturbance in matter that carries energy from one place to another Require matter (solid, liquid, or gas) to travel through a medium The medium is what the wave is traveling through.

Mechanical Waves Caused by energy making a vibration travel through a medium. A vibration is a repeating back-and-forth motion.

Types of Mechanical Waves Put these in the 2 nd row of boxes on your paper Transverse waves Longitudinal waves Surface waves

Types of Mechanical Waves Draw and label both of these.

Transverse Waves

Longitudinal Waves

Like a spring Has compression (area where medium’s particles are close together) and rarefaction (area where medium’s particles are spread out) areas. P waves are longitudinal waves produced by earthquakes.

Surface Waves Like ocean waves Do not usually transport matter

Speed, Wavelength, and Frequency

Period The time required for one cycle (for the wave to get back to where it started)

Frequency The number of complete cycles in a given time Measured in cycles per second or hertz (Hz)

Wave Speed Write down the formula Speed = wavelength x frequency Wavelength in meters Frequency in hertz Speed in meters per second

Speed = wavelength x frequency The string of a piano that produces the note middle C vibrates with a frequency of 264 Hz. If the sound waves produced by the string have a wavelength in air of 1.30 m, what is the speed of sound in air?

Speed = wavelength x frequency A wave is traveling at a velocity of 12 m/s and its wavelength is 3 m. Calculate the wave frequency.

Speed = wavelength x frequency The average wavelength in a series of ocean waves is 15.0 m. A wave arrives on average every 10.0 s, so the frequency is Hz. What is the average speed of the waves?

Speed = wavelength x frequency An FM radio station broadcasts electromagnetic waves at a frequency of 94.5 MHz (9.45 x 10 7 Hz). These radio waves have a wavelength of 3.17 m. What is the speed of the waves?

Speed = wavelength x frequency A wave is traveling at a speed of 18m/s with a frequency of 3 Hz. A second wave is traveling at a speed of 16 m/s with a frequency of 4 Hz. What is the difference between these 2 wavelengths.

Speed = wavelength x frequency Green light has a wavelength of 5.20 x m. The speed of light is 3.00 x 10 8 m/s. Calculate the frequency of green light waves with this wavelength.

Speed = wavelength x frequency The speed of sound in air is about 340 m/s. What is the wavelength of a sound wave with a frequency of 220 Hz (on a piano, the A below middle C)?

Behavior of Waves

Occurs when a wave bounces off a surface that it cannot pass through Does not change speed or frequency of the wave Wave may be flipped upside down Reflection

The bending of a wave as it enters a new medium at an angle Occurs because one side of the wave moves more slowly than the other side Occurs ONLY when the 2 sides of a wave travel at different speeds. Refraction

Reflection & Refraction

The bending of a wave as it moves around an obstacle or passes through a narrow opening A wave diffracts more if its wavelength is large compared to the size of an opening or obstacle. Diffraction

Occurs when 2 or more waves overlap and combine together 2 types: Constructive interference Destructive interference Interference

Occurs when 2 or more waves combine to produce a wave with a larger displacement Constructive Interference

Occurs when 2 or more waves combine to produce a wave with a smaller displacement Destructive Interference

Appears to stay in one place Forms only if half a wavelength or a multiple of half a wavelength fits exactly into the length of a vibrating cord On the next slide A = antinode and N = node. Standing Waves