Question

Two coherent monochromatic point sources S₁ and S₂ of wavelength λ= 600 nm are placed symmetrically on either side of the centre of the circle as shown. The sources are separated by a distance d = 1.8 mm. This arrangement produces interference fringes visible as alternate bright and dark spots on the circumference of the circle. The angular separation between two consecutive bright spots is Δθ. Which of the following options is/are correct?

(A) A dark spot will be formed at the point P₂
(B) At P₂ the order of the fringe will be maximum
(C) The total number of fringes produced between P₁ and P₂ in the first quadrant is close to 3000
(D) The angular separation between two consecutive bright spots decreases as we move from P₁ to P₂ along the first quadrant

Answer 1

As we move from p₁ to p₂ θ decreases and therefore Δθ increases. Therefore (D) is incorrect.