possible .

P(r) = [Al(r) + Am(x)|? = [A,(x)|3 + |42(x)| + 2Re(A(@)A;(r)). (1.13) IA (x) is simply the probability that the electron reaches the plate after passing through $1. We expect this to be a roughly Gaussian distribution pi(r) that is centred on the value , of r at which a straight line from G through the middle of S, hits the plate. (As(r) | should similarly be a roughly Gaussian function pa(x) centred on the intersection at r2 of the screen and the straight line from G through the middle of S2. It is convenient to write Ai = [Aile = vpie's, where of is the phase of the complex number Ai. Then equation (1.13) can be written p(x) = pi(x) + pz(x) + I(x). (1.14a) where the interference term I is I(x) = 2vpi(x)p,(x) cos(d (r) - 62(x)). (1.14b)