what is the maximm and minima of a light wave
is the maxima the peak
and the minima the trough
it makes little sense
because if the minina = the trough,
and that has the least intensity
why is the equilibrium 0
dark fringes at equilibrium
You are getting two things mixed up.
The "dark fringes" maxima and minima are interference patterns caused by light waves adding together such that they combine constructively (peak to peak or trough to trough) or destructively, peak to trough. The maxima and minima of the pattern are not the peaks and troughs of the waves themselves, they are caused by the peaks and troughs of 2 waves adding together.