Equations of a stationary and a travelling waves are as follows y1 = a sin kx cos ωt and y2 = a sin ωt - Kx The phase difference between two points x1 = π3k and x2 = 3π3k are ϕ1 and ϕ2 respectively for the two waves. The ratio ϕ1ϕ2 is

At x1 = π3k and x2 = 3π2k sin Kx1 or sin Kx2 is not zero. Therefore, neither of x1 or x2 is a node Δx = x2 - x1 = 32 - 13πk = 7π6k Since 2πk  > Δx > πk λ > Δx > λ2   k = 2πλ Therefore, ϕ1 = π and ϕ2 = k Δx = 7π6 ∴ ϕ1ϕ2 = 67Note : In case of stationary wave phase difference between any two points is either zero of π .