Difference Between Diffraction and Interference

The difference between diffraction and interference is an important consideration in studying light in physics. The study of these two phenomenons is important because of the many applications of interference and diffraction. One major basis of the difference between diffraction and interference is regarding the occurrence of these two phenomena. Diffraction takes place when a wave comes across an obstacle while interference happens when waves meet each other.

Definition of Diffraction

Diffraction refers to the spreading out of waves when their passing takes place through an aperture. In case the size of the obstacle or aperture is of similar linear dimensions to the incident wave’s wavelength, then its occurrence would be significant. Furthermore, it takes place when the travelling wavelength’s part gets obscured.

Definition of Interference

Interference refers to the phenomenon that takes place due to the meeting of the two waves takes as they travel along with the same medium. Furthermore, the interference causes the medium to take a particular shape. Moreover, this shape is due to the net effect of two individual waves on the medium’s particles.

Difference between Diffraction and Interference

 

Important difference between diffraction and interference

Parameter	Diffraction	Interference
Occurrence	It occurs because of the secondary wavelengths superposition	It occurs due to the light waves superposition that is from two sources
Width of fringes	Unequal	Equal
Intensity of fringe	Not same, in case of diffraction, for all fringes	Same fringe intensity for all the fringes
Obstacle or slit	There is a requirement for it	There is not a requirement for it
Fringe spacing	Non-uniform in the case of diffraction	Uniform in the case of interference
Contrast between maxima and minima	The contrast between maxima and minima is poor	The contrast between maxima and minima is certainly good
Wave propagation direction	It changes after diffraction	It does not change after superposition

More Details about Diffraction

An important answer will be to the question- what is diffraction? Well, it is certainly the phenomenon of light wave spreading when its passing takes place through a small gap or slit. Also, the wavelength should be comparable with all the slit’s dimensions.

An important fact to understand is that light wave does not bend at the edges. This is certainly similar to the case of the large opening. Also, the bending is significantly noticeable in the case of opening that is smaller.

When we take into consideration the very small dimension of the slit, the opening will tend to act as a separate source. Consequently, the spreading of the wave will take place over the entire surface or material after the slit.

More Details about Interference

Interference refers to the act of superposition of multiple light waves whose emission takes place by two coherent sources. Furthermore, these light waves travel in the same medium. Most noteworthy, coherent sources provide a light wave of constant phase difference and the same frequency.

Also, two waves that are coherent in nature will always superpose each other whenever their crossing takes place. Therefore, the superposition of the waves provides the algebraic addition of the existing disturbances because of the presence of separate waves.

The classification of interference can take place into two categories. These two categories are constructive interference and destructive interference. Constructive interference happens when the two superposing waves are of the same phase and amplitude. In contrast, destructive interference happens when the two superposing waves are of the opposing phase but have the same amplitude.

FAQs about Diffraction and Interference

Question 1: Explain a major difference between diffraction and interference?

Answer: One major difference between diffraction and interference is with regards to their occurrence. Furthermore, diffraction occurs due to the secondary wavelengths superposition. In contrast, interference occurs because of the light waves superposition that takes place from two sources.

Question 2: Explain the two categories of interference?

Answer 2: The two categories of interference happen to be constructive interference and destructive interference. Furthermore, constructive interference takes place when the two superposing waves are of similar phase and amplitude. On the other hand, destructive interference takes place when the two superposing waves belong to the opposing phase but their amplitude happens to be similar.

Question 3: Explain the wave propagation direction of diffraction and interference?

Answer 3: The wave propagation direction certainly changes after diffraction. In contrast, the wave propagation direction does not change after superposition with regards to interference.