Interference and Its Types:
What is Interference?
The phenomenon of modification or enhancement in the distribution of intensity in the region of superposition of two or more waves is called Interference.
Principle of Superposition:
When two or more waves arrive at a point of medium simultaneously, each wave producing its own displacement; so that the resultant displacement at that point is the sum of individual displacements.
Types of Interference:
There are two types of Interference-
(1) Constructive Interference- When the resultant amplitude is the sum of the amplitudes due to two waves, interference is known as constructive interference.
For constructive interference, the path difference is a whole number multiple of wavelength i.e.
| Path Difference = 0, λ, 2λ, ……….., nλ and the phase difference is, δ = 0, 2π, 4π, ………., 2nπ |
In constructive interference intensity is maximum.
(2) Destructive Interference- When the resultant amplitude is the difference of two amplitudes, i.e. the resultant intensity is minimum, it gives destructive interference.
But for destructive interference,
| Path Difference = Odd multiple of half wavelength ∴ Path Difference = λ/2, 3λ/2, 5λ/2, …………., (2n + 1) λ/2 and the phase difference is, δ = π, 3π, 5π, ………, (2n + 1)π |
Important Relation:
| Phase Difference = Path Difference x 2π/λ i.e. For phase difference of ‘π’, path difference is λ/2 |
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