Distance of the screen from the slit D = 0.62 m
wave length λ = 539 nm = 539 * 10 -9 m
The width of the central fringe y = 0.055 m
from fig tan θ = ( y / 2 ) / D
friom this wefind θ value
we know condition for 1 st minimum is d sin θ = λ
from this width of the slit d = λ / sin θ
substitue values weget d value
Keep getting the wrong value! any help would be appreciated