By immersing YDSE apparatus into water will the fringe width decrease or no. Of fringes will increase .. and why.??

As in water walength become 1/n time of original and as fringe width directly proportional to wavelength it decreases and no of fringe will increases.

Fringe width is directely proportional to wavelength in medium but inversely proportional to refractive index of medium .As R.I of water > R.I. of air .Therefore fringe width will decrease.No. Of fringe will increase. Hope it helps