3 Wave Motion A wave is the motion of a disturbance. Ex: Ripples in a pondA medium is the physical environment through which a disturbance/wave can travel.Ex: The pondA mechanical wave is a wave that requires a medium to travel through.Ex: Sound Waves (electromagnetic waves are NOT material waves because they can travel in space)
4 Wave Types Pulse Wave: a wave that has one pulse. Periodic Wave: a wave that has continuous pulses.Sine Wave: describe particles that vibrate with simple harmonic motion.Simple Harmonic Motion: any single point on the wave vibrates up and down.Transverse Wave: a wave where the vibrations are perpendicular to the wave motion.-Ex: Light Waves-Crest: the highest point above the equilibrium position.-Trough: the lowest point above the equilibrium position.-Amplitude: distance from equilibrium to crest or trough.-Wave length (λ): distance from crest to crest or trough to trough.Longitudinal Wave: a wave where the vibrations are parallel to the wave motion.-Ex: Sound Waves- Areas that are compressed are density and pressure waves.-Longitudinal Waves can be represented on a waveform (compressed areas arerepresented by crests and stretched areas are represented by troughs).
6 Period, Frequency and Wave Speed Wave Frequency describes the number of waves that pass a given point in a unit of time.Period of Wave describes the time it takes for a complete wavelength to pass a given point.
8 Equations v= Δx/ Δt v= λ/T f= 1/T v= λ/T = f λ v=f λ v= velocity (m/s) f= 1/Tv= λ/T = f λv=f λv= velocity (m/s)Δt= change in time (s)Δx= displacement (m)λ = wavelength (m)T= period of vibration (s)f= frequency (Hz)
9 Waves transfer energy -The greater the amplitude the more energy -The energy transferred is proportional to the square of the amplitude.- Damping: the amplitude of wave gradually diminishes over time as its energy is dissipated.
11 Wave Interaction -Superposition: The combination of two or more waves. -The waves Interact to form Interference Pattern
12 Constructive Interference Constructive Interference: When the resultant wave is larger than the individual displacements.-The two pulses are traveling towards each other on the same side of the equilibrium position-Superposition Principle- When two or more waves travel through a medium at the same time, the resultant wave is the sum of the displacements of the individual waves at each point.-After the pulses pass each other, they have the same shape and are going in the same direction.-Ex: In a concert, the waves travel in all directions and crash into each other but still maintain their own characteristics.
14 Destructive Interference Destructive Interference: When the positive and negative displacements are added, the resultant wave is the difference between the pulses.-The two pulses are traveling towards each other on opposite sides of the equilibrium position-Complete Destructive Interference- When two pulses coincide and the displacements are added, the resultant wave has a displacement wave of zero.-After the pulses pass each other, they have the same shape and are going in the same direction.-Ex: When a compression (particles move together) and a refraction (particles move apart) interfere, there is destructive interference.
16 Reflection -At a free boundary, waves are reflected. -The reflected pulse is upright and has the same pulse as the incident (original) pulse-At a fixed boundary, waves are reflected and inverted.-The displacement is in the opposite direction of the original pulse and the amplitude is the same.
18 Standing Waves-Standing Wave: A wave pattern that results when two waves of the same frequency, wave length, and amplitude travel in opposite directions and interfere-The resultant wave pattern appears to be stationary on the string.-Nodes: Points at which complete destructive interference happen.-Antinodes: The midway point between two adjacent points at which the largest displacement/amplitude occurs.-A standing wave with 2 nodes has a wavelength of 2 times the size between the nodes. (Or 2 times the size of the whole string (L), so 2L)-A standing wave with 3 nodes has a wavelength of 2 times the size between the nodes. (Or 2 times the size of the 1/2 of the string (L), so L)-A standing wave with 4 nodes has a wavelength of 2 times the size between the nodes. (Or 2 times the size of the 1/3 of the string (L), so 2/3L)