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Question: Answered & Verified by Expert
If two waves of the same frequency and amplitude respectively on superposition produce a resultant disturbance of the same amplitude, the waves differ in phase by
PhysicsWaves and SoundMHT CETMHT CET 2017
Options:
  • A π
  • B Zero
  • C π/3
  • D 2π/3
Solution:
2174 Upvotes Verified Answer
The correct answer is: 2π/3
Let the equation of two waves are
y1=asinωt-kx                    i
And y2=asinωt-kx+ϕ ii
When they superpose, the resultant wave is
y=y1+y2
=asinωt-kx+sinωt-kx+ϕ
=a2sinωt-kx+ϕ2cos-ϕ2
=2asinωt-kx+ϕ2cosϕ2
=2acosϕ2sinωt-kx+ϕ2 iii
Comparing Eq. (iii) with (i) or (ii), we get
a=2acosϕ2cosϕ2=12
 cosϕ2=cosπ3  
  cosϕ2=cosπ3  
  ϕ2=π3
or       ϕ=2π3

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