Post on 07-Sep-2018
WAVESSHMTypes of WavesElectromagneticMechanical
TransverseLongitudinalSurface
Wave CharacteristicsReflectionInterferenceStanding Wave
Simple Harmonic Motion
Motion caused by a restoring force that is proportional to displacement
EXAMPLE: Hooks Law
• 𝐹 = −𝑘𝑥
• 𝑘 = 𝑠𝑝𝑟𝑖𝑛𝑔 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡𝑁
𝑚
• 𝑥 = 𝑑𝑖𝑝𝑙𝑎𝑐𝑒𝑚𝑒𝑛𝑡 𝑓𝑟𝑜𝑚 𝑟𝑒𝑠𝑡 𝑝𝑜𝑠𝑡𝑖𝑡𝑖𝑜𝑛
• Force is in the opposite direction from displacement
Simple Harmonic Motion• Period = 𝑻= Time for one oscillation
• Frequency =𝒇= oscillations per second (Hertz)
• 𝑇 =1
𝑓𝑓 =
1
𝑇
• 𝒙 = displacement from rest position
• Amplitude= 𝑨 = maximum displacement from rest position
• Period of Oscillating Mass → 𝑻 = 𝟐𝝅𝒎
𝒌
The Simple Pendulum
•𝑇 = 2𝜋𝐿
𝑔
Electromagnetic wave
Requires No Medium to Travel
Oscillating Electric and Magnetic Field
Travel at the speed of light𝑣 = 𝑐 = 3 ∗ 108𝑚/𝑠
Waves: Transfer Energy
Mechanical Wave
• Requires Medium to travel
• Vibrating Matter
Examples:
• Sound
• Ocean Waves
• Earthquakes
3 Types
Transverse
Longitudinal
Surface
Transverse wavesMedium moves perpendicular to the direction of a wave.
Examples:• Slinky• Crowd Waves at Supercross• Bustin’ a Move
Longitudinal WavesMedium moves parallel to the direction of a wave.
Examples:• Sound Wave• Compressed Slinky• Mosh Pit
Surface WaveMedium moves both parallel and perpendicular to the direction of a wave.
Examples:• Wave Pool• Ocean• Great Lakes
Wave characteristics:
Amplitude, A
•Maximum Displacement from rest position
•Determined by energy
• Wavelength, λ
•Distance between corresponding parts of wave.
• Frequency, f
•Determined by the source
•Oscillations per Unit Time
•Measured in Hertz
•Period, T
• Time for one Oscillations
𝑇 =1
𝑓𝑓 =
1
𝑇
Wave characteristics:
VELOCITY
• Speed of a wave is determined by the medium
• 𝑣 = 𝑓𝜆 (m/s)
Single Medium
SAMPLE PROBLEMA satellite Radio Station has a frequency of 137 MHz.
• Determine the period of the wave?
• Determine the wavelength?
An AM radio wave has a wavelength of 395m
• Determine the frequency of the wave?
• What radio station is it?
Reflection• Occurs when a wave bounces off a barrier
Reflection off Rigid Barrier
Reflected wave has opposite Phase
Reflection off Less-Rigid Barrier
Reflected wave has same phase
Reflection
Any time a wave reaches a barrier part of wave reflected, part of wave transmitted
Ratio of reflected to transmitted depends on properties of the two mediums
Destructive Interference• Amplitude decreases• Pulses meet out of phase
Interference
Constructive Interference• Amplitude increases• Pulses meet In-phase
Constructive & DestructiveInterference
• Occurs when two or more waves meet at the same point in a medium at the same time• Causes amplitude to increase or decrease
Interference
Destructive Interference• Amplitude decreases
Principle of Super Position• the displacement of resulting pulse =
sum of the individual displacements
InterferenceConstructive Interference• Amplitude increases
Principle of Super Position• the displacement of resulting pulse id
sum of the individual displacements
Standing wave
• Standing wave has stationary nodes & antinode
ANTINODEProduced by Constructive Interference• Point of maximum displacement• Pulses meet In-phase
NODEProduced by Destructive Interference• Point of no displacement• Pulses meet out of phase
Resonance
Sound wave and glass oscillate at same frequency.
Produces constructive interference
Amplitude of glass vibrations increases until glass breaks
Resonance
Low frequency produced by wind in the river vibrates at the same frequency as the bridge.
Produces standing wave on Bridge