Physics

# Difference Between Diffraction and Interference in tabular form

The significant difference between Diffraction and Interference is that Interference is the phenomenon if two waves of the same type overlap to give an alternating spatial variation of large and small wave amplitude. On the other hand, Diffraction is the phenomenon of whether a wave passes through an aperture or goes around an object.

In this article, you will explore the difference between diffraction and interference in detail with different examples and diagrams.

## Diffraction Vs. Interference – Overview

The crucial difference between diffraction and interference is that when two separate wavefronts originating from two coherent sources produce interference. Secondary wavelets originating from different parts of the same wavefront are known as diffraction. Although, diffraction and interference are entirely different in nature. The region of minimum intensity is perfectly dark in interference. In diffraction, they are not perfectly dark.

We know that visible light is the type of electromagnetic wave to which our eyes respond. As we have seen previously, light obeys the equation

C= f λ
That interference is a characteristic of energy propagation by waves is demonstrated more convincingly by water waves. Waves in phase on the left produce the upper wave when added together.

### What is interference?

the term interference is used to characterize the superposition of a few coherent waves. In a young double-slits experiment, the interference fringes are all of the equal widths. in double-slit interference. bright fringes are of equal intensity. It causes the medium to take a particular shape.

The shape produces by interference is due to the whole or the net effect of two individual waves on the medium’s particles. Interference is the spreading of waves behind obstacles and the waves stay away from the original route in the same elastic environment. Interference occurs in a way that the superposition of waves starts from varying wavefronts.

It means there is a phase difference between the two waves or they are not coherent waves. when two components are of the same frequency and phase (i.e they vibrate at the same rate and are maximum at the same time) the wave amplitudes are reinforced forming constructive interference. All bright fringes in an interference pattern have the same intensity.

### What are the conditions for interference?

• The light source should be monochromatic.
• The light source should be coherent mean they should not be independent but should be a subsidiary source and derived from a single source.
• The light source should be narrow and have the same intensity.
• For constructive interference path difference between light, rays should be an odd integral multiple of the wavelength of light.

path difference =0,λ ,2λ, 3λ,———–mλ
Where m=0,1,2,3,………

• For destructive interference, the path difference between the light rays should be an odd integral multiple of half the wavelength of light.

Path difference = λ/2 ,3λ/2 ,5λ/2 ,7λ/2 ,…………… (m+ 1 λ/2)
Where m= 0,1,2,3,…..

### Interference examples in real life

• If two stones are dropped into a pool of water, waves spread out from each source, and interference occurs where they overlap
• Two wave trains of light from a double-slit produce interference.

## What is Diffraction?

the term diffraction is used to characterize the superposition of large waves coming from different parts of the same wavefront. in a single slit diffraction pattern, only the non-central maxima are equal width which is half of that of the central, and it happens due to the spreading out of waves passing through an aperture. Aperture refers to the opening of a lens’s diaphragm through which light passes.

In the case of diffraction, the size of the aperture is of similar straight dimensions to the incident wave’s wavelength, and its occurrence is significant. Furthermore, it takes place if the traveling wavelength’s part gets obscured or shaded.

### Diffraction Examples

• The closely spaced tracks on a CD or DVD act as a diffraction grating
• The hologram on a credit card
• Optical Atmospheric diffraction