Single Slit Diffraction

The bending of light around a sharp corner of an obstruction is known as diffraction. When light is incident on a slit the size of the wavelength of light, an alternating dark and brilliant pattern may be seen. This is referred to as single slit diffraction. When light strikes the slit, secondary wavelets emerge from each location, according to Huygens' principle. These wavelets begin in phase and spread in all directions. To reach any place on the screen, each wavelet travels a distinct distance. They arrive with various phases due to the route difference and might interact productively or destructively.

Diffraction Because of the Single Slit

When light strikes a sharp edge of an obstruction, a faint glow can be detected within the geometrical shadow cast by the barrier. This implies that light is bent around a sharp corner. When light flows through an aperture with a dimension similar to the wavelength of light, the impact becomes considerable. When light is incident on a slit with a width corresponding to the wavelength of light, a screen put in front of the slit produces an alternating dark and brilliant pattern. This is referred to as single slit diffraction.

Young's Experiment with a Single Slit

In 1801, Thomas Young's double slit experiment demonstrated the wave structure of light. Monochromatic light is shone through two tiny holes in this experiment. After travelling through each slit, the waves superimpose to provide an alternate brilliant and dark distribution on a distant screen. The intensity and width of all the dazzling fringes are the same.

A single slit experiment involves passing monochromatic light through one slit of finite width and observing a similar pattern on the screen. The width and intensity of the single slit diffraction pattern decrease as we go away from the central maximum, in contrast to the double slit diffraction pattern.

The Phenomenon and Diffraction Formula Explanation

When light strikes the slit, secondary wavelets emerge from each location, according to Huygens' principle. These wavelets begin in phase and spread in all directions. To reach any place on the screen, each wavelet travels a distinct distance. They arrive with various phases due to the route difference and might interact productively or destructively.

If a monochromatic light with wavelength falls on a slit with width a, the intensity on a screen at a distance L from the slit may be represented as a function of Sinθ. In this case, θ is the angle formed by the initial light direction. It is provided by,

Diffraction Bright fringes arise at angles in Maxima and Minima.

a sin θ = mλ with, m = 1, 2, 3 and so on.

Diffraction via single slits appears as an envelope over the interference pattern between the two slits in a double slit configuration.

Width of the fringe

The angular breadth of the central maximum is defined as the angular distance between the two first order minima (on each side of the centre), denoted by:
2 = 2a
Linear width can be written as,

In the diffraction formula, the width of the centre maximum is inversely proportional to the slit width. When the slit width narrows, the centre maximum widens, and when it widens, it narrows. This tendency indicates that light bends more as the aperture size decreases.

Diffraction Conditions

• The light that strikes you should be monochromatic.
• The width of the slit should be similar to the wavelength of the incoming light.

Diffraction Types

• The light source and the screen are both at finite distances from the slit in Fresnel Diffraction. The waves that collide are not parallel.
• Fraunhofer Diffraction occurs when the light source and the screen are both infinitely far from the slit, causing the incident light beams to be parallel.

Did you know that?

• The centre maximum in the diffraction pattern of white light is white, while the other maxima become coloured, with red being the farthest out.
• Any wave can produce diffraction patterns. Subatomic particles, such as electrons, exhibit comparable patterns to light. This finding gave rise to the notion of a particle's wave nature, which is regarded as one of the cornerstones for the development of quantum mechanics.
• Certain crystals' interatomic lengths are comparable to the wavelength of X-rays. Condensed matter physics investigates the crystal structures of various materials using X-ray diffraction patterns.