1. The problem statement, all variables and given/known data http://img842.imageshack.us/img842/4917/physp6.jpg [Broken] I am trying to solve the above problem. However, I am supposed to solve it with the following values: U=54.7eV L=0.2nm Particle is an electron, so: m=9.109E-13kg=0.511eV/c^2 Essentially I am supposed to find the conditions for which no solution is possible using a graphical method. This is where I am stuck. The book that I have does not discuss the graphical method, so I am not sure where to begin with it or where the values come in to play. I have solved it using a traditional method seen below: 2. Relevant equations Schrodinger Equation 3. The attempt at a solution http://img834.imageshack.us/img834/2686/physw6.png [Broken] As can be seen above: k=√[(2mE)/h^2] α=√[(2m(U-E))/h^2] kLcsc(kL)=√[(2mUL^2)/h^2] since kLcsc(kL)=kL/sin(kL) can never be smaller than one, (2mUL^2)/h^2 < 1 Also, since sin(kL) is in the denominator, no solutions would be possible when kL is equal to zero or a multiple of π. To do it graphically, would I simply draw a graph of kLcsc(kL) and show where it is undefined? I am confused. Also where would the values I was given come into play? Thanks!