Question

Discuss briefly diffraction of light from a single slit and draw the shape of the diffraction pattern.

Hint:

In a single-slit diffraction pattern, the central maximum is the brightest, and the intensity decreases as we move to higher-order maxima. The angular position of minima can be found using the formula \( a \sin \theta = n \lambda \).

Answer 1

Step 1: Diffraction is the bending of light around the edges of an obstacle or aperture. It occurs when light passes through a narrow slit or around an object and spreads out. Diffraction is most noticeable when the size of the slit is comparable to the wavelength of light.
Step 2: When monochromatic light passes through a single slit, it creates a pattern on a screen. The pattern consists of a central bright fringe, with alternating dark and bright fringes on either side. The central maximum is the brightest and widest, with subsequent maxima and minima decreasing in intensity.
Step 3: The angular position of the minima in the diffraction pattern is given by the condition:
\[ a \sin \theta = n \lambda \quad \text{for} \quad n = 1, 2, 3, \dots \] where:
- \( a \) is the width of the slit,
- \( \theta \) is the angle of diffraction,
- \( \lambda \) is the wavelength of the light,
- \( n \) is the order of the minima.
Step 4: The diffraction pattern consists of a central maximum, with minima at \( \theta = \pm \sin^{-1} \left( \frac{n \lambda}{a} \right) \), and smaller maxima between the minima.
Conclusion:
The diffraction pattern for light passing through a single slit has a central bright fringe with progressively weaker bright fringes on either side, separated by dark minima.