## College Physics (4th Edition)

(a) $A = 8.0~cm$ (b) $A = 2.0~cm$ (c) The amplitude for constructive interference is larger than the amplitude for destructive interference by a factor of 4.
(a) If the two waves interfere constructively, the amplitude of the resulting wave is the sum of $A_1$ and $A_2$: $A = A_1+A_2 = 5.0~cm+3.0~cm = 8.0~cm$ (b) If the two waves interfere destructively, the amplitude of the resulting wave is the difference of $A_1$ and $A_2$: $A = A_1-A_2 = 5.0~cm-3.0~cm = 2.0~cm$ (c) Note that $8.0~cm = 4\times 2.0~cm$ The amplitude for constructive interference is larger than the amplitude for destructive interference by a factor of 4.