Section 2 - Waves and the Electromagnetic Spectrum
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What do waves do?
They transfer information and energy without transferring matter.
What is amplitude?
Half the displacement from crest to trough.
What is wavelength?
The length of a full wave cycle.
What is frequency?
The number of cycles per second.
What is frequency measured in?
Hertz (Hz), 1Hz = 1 wave per second.
What is a period?
The number of seconds per cycle.
Describe the equation linking wave period and frequency.
Period= 1/ frequency
In transverse waves, which direction do the particles oscillate?
Perpendicular to the direction of energy transfer.
In longitudinal waves, which direction do the particles oscillate?
Parallel to the direction of energy transfer.
What piece of equipment is used to visualise waves?
An oscilloscope.
What are the equations for wave speed?
V=x/t V=f×λ V = wave speed x = distance t = time f = frequency λ = wavelength
What is wave speed?
How quickly a wave moves through a medium.
What is a boundary?
An interface between mediums.
What can happen to waves crossing boundaries?
They can be absorbed, reflected or transmitted, which can lead to refraction.
What is absorption?
The wave’s energy is transferred to the material’s energy store.
What is transmission?
Where the wave is allowed to travel through a material.
What is reflection?
The incoming wave is neither absorbed or transmitted and is instead bounces back away from the material.
What is refraction?
A change in direction during transmission.
How does refraction occur?
Waves travel at different speeds in different mediums depending on density. If a wave crosses a boundary at an angle, this change in speed causes a change in direction.
If a wave slows down in transmission over a boundary, what direction does the wave bend?
Towards the normal.
If a wave speeds up in transmission over a boundary, what direction does the wave bend?
Away from the normal.
What trend do most em waves follow in with wave speed and medium density?
They move slower in denser mediums.
How does the size of the change in speed affect the angle of refraction?
The larger the change in speed, the larger the refraction.
What happens if a wave is transmitted along the normal?
It will not be refracted, instead it will continue to travel in the same direction.