NEET 2021 Model Test Paper 7

In case of diffraction at single slit, the position of minima is given by
d sin θ = nλ ...(1)
and for small θ : sin θ = θ = (y/D) ...(2)
So, from Eqs. (1) and (2), we have :
d(

y

D

)=nλi. e. y=

D

d

(nλ)
So that, y3−y1=

D

d

(3λ−λ)=

D

d

(2λ)
and hence, d=

0.50× (2×6×10−7)

3×10−3

=2×10−4m
=0.2 ‌mm