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Waves - Coggle Diagram
Waves
Reflection
The smoother the surface, the stronger the reflected wave is
Rough surfaces scatter the light in all directions, so appear matt and not reflective
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The electrons will absorb the light energy, then reemit it as a reflected wave
The Ear
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The higher the frequency, the more energy the wave has – which would damage cells in the ear more quickly, and would not be able to work effectively long-term
This, and the fact that we have evolved not needing to hear very high or low frequencies, means the ear only works for a limited frequency range
As it travels down, it still is a pressure air wave
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Absorption
If a material appears green, only green light has been reflected, and the rest of the frequencies in visible light have been absorbed
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They will be absorbed, and then reemitted over time as heat
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Relationships
Increase frequency, velocity increases
Wavelength increases, velocity increases
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Smaller period, higher frequency, greater velocity
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Waves and Energy
What are waves?
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This is shown in the sea, where buoys stay still despite waves passing by them – the waves move, but not the particles
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Equations
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Wave speed (metre/second, m/s) = frequency (hertz, Hz) × wavelength (metre, m)
Transmission
The more transparent, the more light will pass through the material
It can still refract, but the process of passing through the material and still emerging is transmission
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Ultrasound
Sonar
Pulse of ultrasound is sent below a ship, and the time taken for it to reflect and reach the ship can be used to calculate the depth
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Foetal Scanning
Used to create an image of the foetus, allowing measurements to be made
to check the foetus is developing normally
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Measuring Velocity
Sound in air
Make a noise at ~50m from a solid wall, and record time for the echo to be heard, then use speed = distance/time
Have two microphones connected to a datalogger at a large distance apart, and record the time difference between a sound passing from one to the other – then use speed = distance/time
Ripples on water surface
Use a stroboscope, which has the same frequency as the water waves, then measure distance between the ‘fixed’ ripples and use 𝑣 = 𝑓𝜆
Move a pencil along the paper at the same speed as a wavefront, and measure the time taken to draw this line and the length of the line – then use speed = distance/time
Types of Waves
Transverse Waves
Light, or any electromagnetic wave, seismic S waves, water waves
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Longitudinal Waves
Sound waves, seismic P waves
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Infrasound
Infrasound is the opposite of ultrasound – it is a sound wave with a frequency lower than 20Hz – also known as seismic waves
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Effect of Wavelength
Different substances may absorb, transmit, refract or reflect waves depending on their wavelength
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