Note:
From Question number's 21 to 30 rules for Answer marking.
If the Questions have options then you have to answer as follows 
If your answer is option 3 Then fill the OMR sheet as ‘3’
If your answer is options 2&4, Then fill the OMR sheet as ‘24’
if you answer is options 1,3&4 then fill the OMR sheet as ‘134’
And if you answer is options 1,2,3&4 then fill the OMR sheet as ‘1234’
If the question is numerical based, then fill the OMR sheet as usual.
 

 

In the figure shown,  $S_{1}and{S}_2$ are two identical coherent point sources of light which are coherent and out of phase by  ${180}^0$. Taking  $S_1$ as centre, two circular arcs  $\mathcal{l}$ and m of radii 1 m and 2 m are drawn. Taking  $S_2$ as centre, two circular arcs p and q are drawn having radii 2 m and 4 m respectively. It is given that wavelength of wave produced by each source is 4.0m.Then, Choose correct options among the following

1) Constructive interference  is observed at A 
2) Constructive interference  is observed at B 
3) Constructive interference  is observed at C 
4) Constructive interference  is observed at D