Rex_chaos
hi all,
Suppose there is a plane wave u=exp(-i k x), where k is a wavenumber. How to determine it's moving direction?
Suppose there is a plane wave u=exp(-i k x), where k is a wavenumber. How to determine it's moving direction?
Yes, I know the result. However, how to prove that +k corresponding to a wave moving to the right?Aexp(ikx)+Bexp(-ikx)
Where the plus is for moving to the right en the minus for moving to the left...
It is true that in the trivial case which has the form E ~ exp(-kx) the wavevector gives the direction of the traveling wave. However, examine a case with superpositioned wave patterns having unequal direction, orientation and magnitude. You will see that calculating the Poynting vector gives the most straight-forward method for determining the direction of an EM wave.Originally posted by heumpje
Perhaps i missed something during my physics classes but the k...
It is common practice to absorb the time dependence in the magnitude coefficient as I shown above. I assume Rex_chaos meant:Originally posted by pmb
To determine in which direction the wave propagates you need to specity the time dependance as well as the space dependance. You've only given the spatial dependance of the phasor. There are two choices of a time dependance corresponding to two choices of the sign of "wt".
Pete