Topic: Properties of Waves
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Transcript of Topic: Properties of Waves
Topic: Properties of Waves
• Essential Question: What vocabulary do we use to accurately describe the properties of waves and how they interact with other waves or objects?
What is a wave?
• Waves• Medium• Resonance• Interference
• Constructive interference• Destructive Interference
• Transverse Wave• Longitudinal Wave
• Amplitude• Frequency• Period
• Wavelength• Reflection• Refraction• Diffraction• Polarization• Phase
• Doppler Effect• Node
• Antinode
What is a wave?
• Wave:– A rhythmic disturbance that carries energy
through matter or space• Wave Pulse:– A single bump or disturbance that travels through
a medium
What is a wave?
• Waves• Medium• Resonance• Interference
• Constructive interference• Destructive Interference
• Transverse Wave• Longitudinal Wave
• Amplitude• Frequency• Period
• Wavelength• Reflection• Refraction• Diffraction• Polarization• Phase
• Doppler Effect• Node
• Antinode
What is a medium?
• Medium:– Something that the wave travels through.
• Examples:– The medium of the waves in yesterday’s lab was
the beads.– The medium of an ocean wave is water.– What medium do sound waves travel through?
IMPORTANT!
• THE MEDIUM DOESN’T GO ANYWHERE!– The medium only moves back and forth or up and
down, but on average, it stays in the same place!– Don’t believe me? Watch the green beads in te
simulation from the lab:
Describing Waves:
• Waves• Medium• Resonance• Interference
• Constructive interference• Destructive Interference
• Transverse Wave• Longitudinal Wave
• Amplitude• Frequency• Period
• Wavelength• Reflection• Refraction• Diffraction• Polarization• Phase
• Doppler Effect• Node
• Antinode
Parts of a Wave
Describing Waves:
• Amplitude:– The height of the wave– Measured from the MIDDLE – where the medium
would be if there was no wave passing through it. • Wavelength:– Measured in meters. Represented by λ
Describing Waves:
• Waves• Medium• Resonance• Interference
• Constructive interference• Destructive Interference
• Transverse Wave• Longitudinal Wave
• Amplitude• Frequency• Period
• Wavelength• Reflection• Refraction• Diffraction• Polarization• Phase
• Doppler Effect• Node
• Antinode
• Frequency:– The number of complete oscillations/cycles it
makes each second– f = 1/T
f = frequency (units of Hz or 1/s) T = period (units of s) – the time for one complete
cycle
Speed of a wave
So frequency is not the speed of the wave. Formula:
v = λfλ = wavelength (meters)f = frequency (1/s or Hz)units = m/s
Types of Waves:
• Waves• Medium• Resonance• Interference
• Constructive interference• Destructive Interference
• Transverse Wave• Longitudinal Wave
• Amplitude• Frequency• Period
• Wavelength• Reflection• Refraction• Diffraction• Polarization• Phase
• Doppler Effect• Node
• Antinode
Types of Waves
– Transverse wave – a wave that vibrates perpendicular to the direction of wave motion
– Longitudinal wave – a wave that moves parallel to the disturbance.• Example: Sound wave
What kind of wave is this?
What kind of wave is this?
More Terminology• Antinode – Where the largest displacement
is located in a wave (largest amplitude)• Node – Where the smallest displacement is
located in a wave (smallest amplitude)• Standing wave:– When a wave appears to be standing still
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Wave Interference
• Destructive interference:– When two waves collide and
result in a smaller wave• Constructive interference:– When two waves collide and
result in a larger wave• Principle of superposition:– The algebraic sum of the
heights two waves that collide is equal to the height of the resulting wave
Principle of superposition
• When two waves collide, or interfere, they add together.
• The blue wave and the green wave add together to make the black wave
Wave Interaction Terminology
• Incident wave – A wave that strikes a boundary
• Reflected wave – A wave that returns after striking a boundary
Other Wave Interactions
• Reflection:– When a wave bounces off an object– Law of Reflection – The angle of incidence is equal
to the angle of reflection.
• Refraction:– The change in direction of a wave at the boundary
between two different media
• Diffraction– The spreading of waves around the edge of a
barrier or through a hole.– Often results in a planar wave changing into a
circular wave