4. Scattering off a delta function and a wall. [15 points] Consider our usual one-dimensional potential with V(x) = co for r 0 off this potential. We have 2mEa ( ka) = = mag 12 , unit free. (a) Calculate the phase shift 6(k). Write the answer in the form sin (ka) tand = h(ka; A) where h(ka; A) is a function you must determine. Explain how, with o known, one readily finds the amplitude A() multiplying the 'sin' function in the wave- function for 0