The maximum intensity of fringes in Young's experiment is I. If one of the slit is closed, then the intensity at that place becomes `I_o`. Which of the following relation is true?

Explanation

Suppose slit width's are equal, so they produces waves of equal intensity say I'. resultant intensity at any point `I_R=4 I' cos^2 phi` where `pi`is the phase difference between the waves at the point of observation.
For maximum intensity `phi=0^@impliesI_(max)=41'=I`.....(i)
If one of slit is closed, Resultant intensity at the same point will be I' only i.e., `I_0`.....(ii)
Comparing equations (i) and (ii) we get
`I=4I_0`