Hello guys I have a question about constructive/ destructive interference. I know that in single slit and double slit patterns that the dark fringes=destructive interference (minima) bright fringes = constructive interference (maxima) I do know that the formula's are as follows: Single slit: constructive: path differene= mlambda (a)sin(theta)= m lambda where m=1,2,3,4 etc... destructive: path difference= 1/2(m) (lambda) (a) sin (theta)= (m)lambda where m= 1,3,5,7 etc... double slit: constructive interfernce: path differene= mlambda (d)sin(theta)= m lambda where m=1,2,3,4 etc... destructive: path difference= 1/2(m) (lambda) (d) sin (theta)= (m)lambda where m= 1,3,5,7 etc... So yes I would like you guys to tell me if these formula's are right.... i have been looking in my notes and it really isn't clear. One last thing... how do you know if you have a constructive pattern or a destructive pattern just by looking at the quesition (if it doesn't tell you to find minima or maxima). Thank you