If two waves having amplitudes a and b make superposition the resultant amplitude A is given as A = 1 √(a2 + b2 + 2ab cosφ) where φ is phase constant. The intensity (I)2 is directly proportional to square of amplitude. I α A2 I.e. I α (a2 + b2 + 2ab cos φ )In case of constructive interference cos φ = 2np. Imax = k (a + b)2While in case of destructive interference Imax = k (a – b)2Light wave from two coherent sources of intensity ratio 81 : 1 produce interference. Using these informationchoose correct answer in the following.1.The ratio of maxima and minima in the interference pattern is.a) 9:1 b) 81 : 1 (C) 25 : 16 (D) 16 : 252.The ratio of amplitudes of light waves from two sources is(A) 1 : 4 (B) 4 : 1 (C) 2 : 1 (D) 1 : 23.(The ratio of amplitudes of two sources is(A) 9 : 1 (B) 81 : 1 (C) 1 : 9 (D) 1 : 81

Radhika Batra , 11 Years ago

Grade 11