1.Longitudinal waves - oscillation is
parallel to the direction of travel
2.Wavelength - distance between 2
compressions or rarefactions
3.Frequency—number of waves passing per second
1.Transverse waves - oscillation is perpendicular to the direction of travel
2.Wavelength - distance between 2
peaks or troughs
3.Frequency—number of waves passing
per second
Key words / phrases
1.Diffraction happen when waves
pass through a gap.
2.The wave energy spreads out in all
directions
3.Most diffraction occurs when the
wavelength is about the same size as
the gap.
4.Sound diffracts through doorways
so you can hear around corners.
5.Light needs very small gaps to
diffract.
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1.Wavespeed = wavelength x frequency
2.Wavespeed units are m/s
3.Wavelength units are m
4.Frequency units are Hz . 10Hz means 10
waves passing per second
5.Knowing 2 of the values lets you work out
the third—make sure you convert to the correct units
Wave—something that transports energy from an oscillating system
Oscillation—a movement or change that repeats itself in time.
Transverse—a wave where the oscillation is perpendicular to the direction of travel
Longitudinal—a wave where the oscillation is parallel to the direction of travel
Wavelength—the distance between two peaks or two compressions
Wave speed—the speed at which the energy is transported
Frequency—the number of complete waves passing a point in 1 s
EM spectrum—a series of waves with different wavelengths organised into bands
(radio, micro, infra-red, visible, ultra-violet, X-rays and gamma) that transfers electromagnetic energy.
9. Reflection— where waves bounce off surfaces to change direction
10. Refraction— where waves change direction as they pass through one medium to
another due to a speed change.
11. Diffraction—where waves spread out when they pass through a gap about the same
dimension as their wavelength.
1.Waves can be reflected by surfaces
e.g. sound by hard surfaces, light by
shiny surfaces.
2.The law of reflection says the angle
of incidence = angle of reflection.
3. Reflections can be specular (like in
a mirror) or diffuse (light reflecting
off a desk)
1.The electromagnetic spectrum is a series of waves
transporting electromagnetic
energy
2. Many everyday waves we
rely on are EM waves.
3.They vary in wavelength
and frequency
Normal
1.Waves can be refracted when they
pass from one medium to another.
2.If the wave slows down, it will bend
towards the normal (e.g. air to glass)
3.If the wave speeds up, it bends
away from the normal (e.g. glass to
air)
1.The uses of EM waves are either communication
or medical
2. Low frequency EM waves tend to be used for
communication e.g. radio (radio/TV), Microwave
(phones/satellites), IR (remote controls) and visible
(seeing things, fibre optics)
3.High frequency waves tend to be used for medical
Purposes e.g. UV (sterilising), X-rays(Photographing
broken bones, CAT scans, radio therapy), gamma
(Radiotherapy, gamma cameras)
4. UV is also used for preventing forgeries
(fluorescent passports/bankers cards) and microwaves for cooking