This chapter examines the case of sudden creation of a lossless finite extent plasma slab. The transient solution is obtained through the use of Laplace transform. The solution is broken into two components: an A component that in steady state has the same frequency as the incident wave frequency and a B component that has an upshifted frequency. The chapter illustrates a problem that features a temporal discontinuity resulting from a sudden temporal change in the properties of the medium and spatial discontinuities owing to the confinement of the plasma in space. Several interesting phenomena take place due to these discontinuities. The temporal discontinuity results in the creation of two new waves in the plasma medium. These are termed the B waves. They have the same wave number as that of the incident wave but have a frequency that differs from that of the incident wave.