Question

Two radio frequency point sources S₁ and S₂ , separated by distance 2.5 m are emitting in phase waves of wavelength 1 m. A detector moves in a large circular path around the two sources in a plane containing them. The number of maxima that will be detected by it over the complete circular path, are

(A) 16 

(B) 12 

(C) 10 

(D) 8

Answer 1

Correct option (C) 10

Explanation: 

At point A, the path diference is 2.5 and at B, path difference is zero. While moving from A to B, path difference changes from 2.5 to zero, making two maxima corresponding to 2 and (excluding B). B is common for both upper quarter circles hence there are five maxima in one half circle, making 10 in total circular movement.