17. A beam of particles of energy E and incident upon a potential step of U. = & E is described by the wave function 'inc (x) = leikx (a) Determine completely the reflected wave and the wave inside the step by enforcing the required continuity conditions to obtain their (possibly complex) amplitudes.(b) Verify by explicit calculation that the ratio of reflected probability density to the incident proba- bility density is 1. incident unon