1. The problem statement, all variables and given/known data For two coherent sources vibrating in phase separated by 4.5(lambda), what are the numbers of antinodal and nodal lines? 2. Relevant equations No. of nodal lines equals twice the floor function of separation over wavelength. 3. The attempt at a solution No. of antinodal lines= 2(4)+1=9 No. of nodal lines= 2(4)=8 Is this correct?