two lasers are shinning on a double slitSolutionfor laser 1

Solution

for laser 1

distance from center to second order maximum, y2 = 2*lamda*R/d

= 2*(d/20)*4/d

= 0.4 m

for laser 2

distance from center to third maximum, y3 = (5/2)*lamda*R/d

= (5/2)*(d/15)*4/d

= 0.667 m

so, require dalat_y = 0.667-0.4

= 0.267 m <<<<---------Answer