40 The basics of quantum mechanics Shou'n in Fig. l.l3 are plots of four such two-dimensional u,ave functionsfor rr. and n, values of (1,1), (2,1), (1.2) and (2.2). respecti'cl.v. Nore that thefunctions vanish on the boundaries of the box, and notice hou, tlre nurnber ofnodes (i.e..