Part I - Characteristics of Waves Waves & Sound Part I - Characteristics of Waves Learning Goal SOL PS 8 – The student will investigate and understand characteristics of sound and technological applications of sound waves.

Essential Questions What are the measurable properties of waves? What is a wave? What are the measurable properties of waves? How are wavelength, frequency, speed calculated?

A. What is a wave? Waves rhythmic disturbances that carry energy through matter or space (Video Clip) Medium material through which a wave transfers energy solid, liquid, gas, or combination electromagnetic waves don’t need a medium (e.g. visible light) Video Clip

A. What is a wave? Two Types: Longitudinal Transverse

A. What is a wave? Transverse Waves medium moves perpendicular to the direction of wave motion

A. What is a wave? Longitudinal Waves (a.k.a. compressional) medium moves in the same direction as wave motion

A. What is a wave? Wave Anatomy compression wavelength rarefaction Amount of compression corresponds to amount of energy  AMPLITUDE.

B. What are the measurable parts of a wave? Your ideas?

B. What are the measurable properties of wave? Simulation: Waves on a String Answer the following: 1) How does the amount that I wiggle the wrench affect the wave? 2) How does the speed that I wiggle affect the wave? 3) Switch to “Oscillate”: What happens when I change amplitude? What happens when I change frequency? What happens when I change damping? Explain these three underlined words.

B. What are the measurable parts of a wave? Wave Anatomy corresponds to the amount of energy carried by the wave crests wavelength amplitude nodes troughs

B. What are the measurable parts of a wave? Frequency ( f ) # of waves passing a point in 1 second Hertz (Hz) 1 second shorter wavelength  higher frequency  higher energy

C. How are wave properties calculated? Velocity ( v ) speed of a wave as it moves forward depends on wave type and medium v =  × f v: velocity (m/s) : wavelength (m) f: frequency (Hz)

C. How are wave properties calculated? EX: Find the velocity of a wave in a wave pool if its wavelength is 3.2 m and its frequency is 0.60 Hz. GIVEN: v = ?  = 3.2 m f = 0.60 Hz WORK: v =  × f v = (3.2 m)(0.60 Hz) v = 1.92 m/s  v f

C. How are wave properties calculated? EX: An earthquake produces a wave that has a wavelength of 417 m and travels at 5000 m/s. What is its frequency? GIVEN:  = 417 m v = 5000 m/s f = ? WORK: f = v ÷  f = (5000 m/s) ÷ (417 m) f = 12 Hz  v f

D. How do waves behave? Reflection occurs when a wave bounces back after striking a barrier.

D. How do waves behave? Refraction occurs when a wave bends as it passes from one medium to another.

D. How do waves behave? Video Clip: Wave Interference

LET’S REVIEW! (copy into notes) energy A wave is created when a source of ________ causes a vibration to move through a _________. There are several types of mechanical waves including _____________ waves and ____________ waves. Draw an example of each. medium longitudinal transverse

LET’S REVIEW! (copy into notes) A _____________(compression) wave is a wave in which the vibration of the medium is ____________ to the direction in which the wave travels. This type of wave consists of a repeating pattern of _____________ and _____________. longitudinal parallel compressions rarefactions

LET’S REVIEW! (copy into notes) All waves exhibit certain characteristics: __________, ___________, and ___________. Draw a transverse wave and label the three things listed above. Draw a longitudinal wave and label the three things listed above. wavelength amplitude frequency