Where s is the distance, v is the propagation speed, and t is time.Įach point on the wavefront emits a wave at speed, v. If you get stuck, do let us know in the comments section below, and we will get back to you at the earliest.\] We hope this detailed article on the Diffraction of Light helps you prepare. When white light enters the grating, the light components are diffracted at angles that are determined by the respective wavelengths. The simplest type of grating is one with a large number of evenly spaced parallel slits. But interference is the result of the superposition of light waves from two coherent sources.Īns: A diffraction grating is an optical element that divides light composed of lots of different wavelengths(e.g., white light) into light components by wavelength. What is the difference between Diffraction and interference?Īns: The crucial difference between Diffraction and interference is that Diffraction of light occurs due to the superposition of secondary wavelets that generates from various parts of a wavefront. Diffraction Grating is used to transform the light into its spectrum, and X-ray diffraction is used in crystallography. What is the application of Diffraction of light?Īns: i. This Diffraction does not even play any role in the formation of a rainbow. Is a rainbow an example of Diffraction?Īns: No, the rainbow is not an example of Diffraction because a rainbow is formed due to reflection and refraction. The hologram on a credit card also works with the principle of Diffraction. For example, when you observe a CD or DVD, the closely spaced tracks on a CD or DVD act as a diffraction grating to form the familiar rainbow pattern. How can we see Diffraction in our daily life?Īns: The effects of Diffraction are usually seen in everyday life. The intensity of central maxima will be maximum, and the intensity decreases rapidly on either side. Where \(a\) is the width of the slit, \(λ\) is the wavelength of light and \(m = ☑,\,☒,\,☓\)… Maxima and minima will form in alternate order. Therefore, we can conclude that waves from the upper half of the slit will interfere with waves from the lower half destructively when:. When any two rays originate at points ( at phase difference \(180°\)), then it is separated by half the slit width. The two waves cancel each other if this path difference is exactly half a wavelength (corresponding to a phase difference of \(180°\)). Similarly, the path difference between rays \(2\) and \(4\) is also \((a/2) \sin θ\). As these two rays travel toward a viewing screen far to the right of Fig 3, and ray \(1\) travels farther than ray \(3\) by an amount equal to the path difference of \((a/2) \sin θ\), where \(a\) is the width of the slit. Keeping in mind that all the waves are in phase as they leave the slit, now consider rays \(1\) and \(3\). To analyze the diffraction pattern, first divide the slit into two halves, as shown in Fig 3. So that the light from one portion of the slit can interfere with light from another portion of the slit, and the resultant light intensity will depend on the direction \(θ\) and it can be obtained on a screen. Now, According to Huygens’s principle, each portion of the slit acts as a source of light waves. Let us consider waves coming from various portions of the slit in the given figure. Diffraction of Light by a single slit of width a Plane diffracting waves are conserved using a convex lens to produce a diffracting pattern.įig. The plane or horizontal wavefront are connected using a convex lens to produce a diffraction pattern.ĭ. The incident wavefronts are horizontal.Ĭ. The screen and the source are an infinite distance from each other.ī. The important points for Fraunhofer Diffraction are given below:Ī. This can be achieved either by placing the light source far from the opening used to create the Diffraction, as shown in the figure below. Fraunhofer Diffraction: This occurs when all the rays passing through a narrow slit are approximately parallel to one another. The wavelength of the light used should be comparable to the size of the obstacle. The source of light should be coherent.Ģ. Diffraction is a general characteristic exhibited by all types of waves, such as sound waves, light waves, water waves, or matter waves.Įssential Condition for observation of Diffraction.ġ. So, it is possible when both are equal or closer in size for a considerable amount of bending that can be seen with the naked eye. The bending won’t be noticeable if the opening is much larger than the wavelength of light.
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