How does amplitude differ across the diffraction pattern?

The amplitude across the diffraction pattern varies, being highest at the central maximum and decreasing towards the fringes.

In a diffraction pattern, the amplitude of the light waves changes across the pattern. This is due to the interference of light waves, which is the fundamental principle behind diffraction. When a wave encounters an obstacle or a slit that is comparable in size to its wavelength, it bends around it, creating a new wavefront. This phenomenon is known as diffraction.

The diffraction pattern is characterised by a series of bright and dark fringes. The bright fringes, also known as maxima, are areas where the waves interfere constructively, meaning the crests and troughs of the waves align. This results in a higher amplitude, which corresponds to a higher intensity of light. The central maximum, which is the brightest spot in the diffraction pattern, has the highest amplitude.

On the other hand, the dark fringes, or minima, are areas where the waves interfere destructively. Here, the crest of one wave aligns with the trough of another, cancelling each other out and resulting in a lower amplitude, which corresponds to a lower intensity or even absence of light.

As you move away from the central maximum towards the edges of the diffraction pattern, the amplitude decreases. This is because the path difference between the waves increases, leading to more destructive interference and hence a lower amplitude. The intensity of the fringes also decreases, which is why the fringes appear to fade out towards the edges of the pattern.

In conclusion, the amplitude across the diffraction pattern is not constant but varies due to the interference of light waves. It is highest at the central maximum and decreases towards the fringes, reflecting the changing intensity of the light across the pattern. Understanding this concept is crucial for interpreting diffraction patterns and understanding the wave nature of light.