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zak8000
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Homework Statement
a particle of kinetic energy E is incident from left on a potential barrier,height U, situated at the origin.the barrier is infinitely wide and E>U
obtain an expression for the reflection coefficient R of the particle as a fuction ratio e=E/U
Homework Equations
The Attempt at a Solution
to left of barrier wavefunctions are free particle waves
barrier at x=0
psi(x,t)=Aexp(ikx-wt)+ Bexp(-ikx-wt) x<0
within barrier wavefunction also is oscillatory
E=h(cross)*w
considering case for E<U and using TISE on psi(x,t) within barrier we get
a=([2m(U-E)]^0.5)/h(cross)
but now E>U and as a result a becomes imaginary. introducing new wavenumber L and barrier wavefunction becomes
psi(x,t) =Cexp(-iLx-wt)+Dexp(iLx-wt) x>0 (note this is equation is only for a barrier of finite width)
but now everywhere to right from origin x=0 is the barrier wavefunction given above . to keep psi(x,t) from diverging for large x we must take D=0 leaving only decaying wave and this is where i am up to i was just wanting to know if i am on the right track