A Brief Introduction to Space Plasma Physics.pdf - Institute of ...

•Some elementary wave concepts
–For a plane wave propagating in the x-direction with
wavelength λ and frequency f, the oscillating quantities
can be taken to be proportional to sines and cosines.
For example the pressure in a sound wave propagating
along an organ pipe might vary like
p
=
p0 sin( kx −ωt)
–A sinusoidal wave can be described by its frequency
k r
r r r r
r r
B( r,
t)
= B0 cos(
r
k ⋅
−ωt
v
) + i sin( k ⋅
−ωt)
r
B( r,
t)
= B0 exp{ i(
k ⋅
−ωt)}
and wave vector . (In the organ pipe the frequency is
f and ω = 2π f . The wave number is k = 2π λ ).
r
( )
ω