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The phenomenon of interference and diffraction can be explained by the wave theory of light. The word ‘interference’ means the superposition of two or more waves, which results in the formation of lower, greater or similar amplitudes of the resultant wave at the same place and at the same time. Diffraction is the phenomenon of bending of light around the sharp corners and the spreading of light within the geometrical shadow of opaque obstacles. Â
Interference – definition
Interference means when two or more waves meet or superpose each other, this phenomenon depends on the arrangements of troughs and peaks of the waves that overlap which may cancel each other totally or to some extent and might add up to one another. Interference means a physical effect that occurs due to a combination of two or more waves. The superposition of wave is defined as when a pin is dropped in a water-filled tank, some circular waves are visible and when another pin is dropped next to the previous pin within a few seconds, some more waves are visible in due time and when these waves superimpose on each other is known as a superposition of wave. The resultant waves have an amplitude which is the summation of the displacement due to the individual waves. There are two types of interference – Constructive interference and Destructive interference. Constructive interference is defined as when the two or more waves have the same phases and move in a similar direction, then their amplitude is added which is equivalent to the summation of the individual wave’s amplitude. A new wave is formed which looks exactly like the original waves but there is a difference between these two waves is that the amplitude of the new wave is larger than the original wave in constructive interference.Â
Diffraction – definition
Diffraction is defined as the phenomenon of lying out of waves around an opaque object. Not producing sharp shadows is one of the outcomes of diffraction. This phenomenon is the consequence of interference and is mostly taken into consideration when the radiation’s wavelength can be compared to the obstacles’ linear dimensions. Diffraction occurs with very small particles like neutrons, atoms, and electrons; with electromagnetic radiations such as X-ray, light, gamma rays, etc.
Difference between diffraction and interference
Sl. No. | Diffraction | Interference | ||
1 | Diffraction is defined as the event of bending of a wave around an object which is opaque and the shadow which is formed as the result of this is not a sharp shadow. | Interference is defined as, when two or more waves superpose with each other, at the same place and at the same time resulting in the formation of a lower, similar, or greater amplitude of the resultant wave. | ||
2 | The diffraction pattern occurs due to the formation of a secondary wave that is emerging from a particular wave. Therefore, it simply means that there is only one coherent source that is needed. | The interference pattern occurs due to the two coherent and independent waves when they superpose with each other. | ||
3 | Between maxima and minima, there is a poor contrast. | Between maxima and minima, good contrast is present. | ||
4 | In the case of diffraction, the dark fringe’s intensity is not equal to zero. | Zero is the intensity of the dark fringe in case of interference. | ||
5 | In diffraction, the bright fringes are inversely proportional to the intensity. So, as the intensity decreases as the bright fringes increase. | For interference, each of the bright fringes has similar intensity. | ||
6 | For dark fringes – a) The phase difference: d = 2n b) Path difference: D = 2nλ/2 | For dark fringes – a) The phase difference: d = (2n – 1) b) Path difference: D = (2n – 1)/2 | ||
7 | For bright fringes – a) The phase difference: = (2n -1) b) Path difference:      ∆ = (2n -1)λ/2 | For bright fringes – a) The phase difference: = 2n b) Path difference:     ∆ = n | ||
Conclusion
It is to be concluded that interference means when two or more two waves meet or superpose each other. Diffraction is defined as the event of bending of a wave around an object which is opaque and the shadow which is formed as the result of this is not a sharp shadow.Â
