Table of Contents

## 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 |