Young's double slit experiment with two sets of slits

[Apashanka das]

1. The problem statement, all variables and given/known da

Homework Equations

Interference minima is asinΘ=nλ/2 where n=1,3,5,7...
[/B]

The Attempt at a Solution

Putting ab/(2sqrt(b^2/4+d^2))=λ/2 for first order minima
And solving for d I get (b/2)*sqrt((2a/λ)^2-1) in which only the 2 factor differs in front of a in the square root
from the correct ans which is option 2 in the question
I may be wrong but where I didn't get it?

 

[Chandra Prayaga]

Why did you start with the condition for interference minima? The passage of light through the first slit is diffraction.

 

[ehild]

1. The problem statement, all variables and given/known daView attachment 220386 View attachment 220386

Homework Equations

Interference minima is asinΘ=nλ/2 where n=1,3,5,7...
[/B]

Check the formula in red.

 

[Apashanka das]

Check the formula in red.

yes I have used this formula

 

[ehild]

yes I have used this formula

The formula is wrong .
http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/sinslit.html