A single-slit diffraction pattern is formed on a distant screen. If the width of the single slit through which light passes is reduced, what happens to the width of the central bright fringe? Assume the angles involved remain small.
The central bright fringe becomes wider.
The central bright fringe becomes narrower.
The central bright fringe remains the same size.
When the width of the single slit through which light passes is reduced, the width of the central bright fringe will become narrower. This phenomenon can be explained by the principle of diffraction.
Diffraction occurs when light passes through a small opening like a single slit. As the light waves pass through the slit, they spread out and interfere with each other. The interference pattern creates a series of bright and dark fringes on a screen placed at a certain distance from the slit.
The central bright fringe is the widest and brightest fringe in the diffraction pattern. It is formed when light waves coming from the center of the slit constructively interfere with each other, resulting in larger amplitudes and higher intensity.
When the width of the slit is reduced, the amount of diffraction increases. This means that the spreading out of the light waves is more pronounced. As a result, the constructive interference at the center of the slit becomes less significant, leading to a narrower central bright fringe.
Therefore, when the width of the single slit is reduced, the width of the central bright fringe will also become narrower.
sin T = l / a
Does this tell you anything about the angle of the central fringe, vs the width a? When a is large, T is smaller.