Destructive Interference


There are many interesting wave phenomenon in nature, that cannot be defined by an individual wave. To comprehend destructive interference phenomenon, we must examine based on combination of waves. To examine these, we apply the principle of Superposition which says:

“If two or more waves are traveling in a medium, the resulting wave function is the algebraic total of the individual waves function.”

When the waves of identical frequency and equivalent amplitude are superimposed, the process of interference takes place. When two waves of a similar frequency move in a medium at the same time and towards the same direction, because of their superposition, the resulting intensity of the medium at any point is dissimilar from the sum of their intensities. At some points, the strength of the resultant wave bears a larger value, while at certain points the value is very small. In this segment, we will concentrate more on Destructive Interference.

Destructive Interference Definition:

When two waves of a similar frequencies travel in a medium, the resultant at different points is dissimilar from the sum of their intensities because of their superposition. At one point it is too less and negligible which we call it as Destructive Interference.

In the above figure, A and B are the two waves of similar frequencies traveling in a medium in a similar direction.

Equation – Destructive Interference:

  1. The phase difference among two waves an odd multiple ofπ that is,
  2. The difference between the path of two waves is an odd multiple ofλ/2, Δ = (2n–1) λ/2 .
  3. The time interval among the two waves is an odd multiple of T/2, θ = (2n–1) T/2.
  4. The resultant amplitude is equivalent to the difference between amplitudes of individual waves.

Destructive Interference Examples:

Here are some examples of Destructive Interference:

  1. Gravitational waves are a specimen of Destructive Interference.
  2. Light beams demonstrate Destructive Interference.
  3. Moving electrons and radio waves also perform Destructive Interference.

Stay tuned to BYJU’S to know more about destructive interference, coherent sources and much more.

Practise This Question

A body moves at a speed of 20kmhr for the first 2 hours then it moves at the speed of  30kmhr for the next 1 hour. What is the total distance travelled by the body?