How things wave
How things wave
Introduction to WAVES.
So - Waves.....
We spoke about energy. Energy can, as it turns out, travel in waves. In fact, you can think of a wave as a traveling disturbance, capable of carrying energy with it. For example, light "waves" can have energy - like solar energy. Ocean waves can certainly carry energy.
There are several wave characteristics (applicable to most conventional waves) that are useful to know:
amplitude - the "height" of the wave, from equilibrium (or direction axis of travel) to maximum position above or below
crest - peak (or highest point) of a wave
trough - valley (or lowest point) of a wave
wavelength (lambda - see picture 2 above) - the length of a complete wave, measured from crest to crest or trough to trough (or distance between any two points that are in phase - see picture 2 above). Measured in meters (or any units of length).
frequency (f) - literally, the number of complete waves per second. The unit is the cycle per second, usually called: hertz (Hz)
wave speed (v) - the rate at which the wave travels. Same as regular speed/velocity, and measured in units of m/s (or any unit of velocity). It can be calculated using a simple expression:
There are 2 primary categories of waves:
Mechanical – these require a medium (e.g., sound, guitar strings, water, etc.)
Electromagnetic – these do NOT require a medium and, in fact, travel fastest where is there is nothing in the way (a vacuum). All e/m waves travel at the same speed in a vacuum (c, the speed of light):
c = 3 x 10^8 m/s
Yes, this is the same speed of light we've talked about already.
First, the electromagnetic (e/m) waves:
General breakdown of e/m waves from low frequency (and long wavelength) to high frequency (and short wavelength):
Radio
Microwave
IR (infrared)
Visible (ROYGBV)
UV (ultraviolet)
X-rays
Gamma rays
In detail, particularly the second image:
We'll spend more time with electromagnetic waves after we first talk about mechanical waves.
Mechanical waves
Mechanical waves include: sound, water, earthquakes, strings (guitar, piano, etc.)....
Again, don't forget that the primary wave variables are related by the expression:
v = f l
speed = frequency x wavelength
(Note that l should be the Greek symbol 'lambda'. See the boxed equation above.)
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