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Question:

Diffraction pattern of a single slit consists of a central bright band which is Wide, and is flanked by alternate dark and bright bands of equal intensity; Narrow, and is flanked by alternate dark and bright bands of equal intensity; Wide, and is flanked by alternate dark and bright bands of decreasing intensity; Narrow and is flanked by alternate-dark and bright bands of decreasing intensity.

Wide, and is flanked by alternate dark and bright bands of equal intensity

Narrow, and is flanked by alternate dark and bright bands of equal intensity

Narrow and is flanked by alternate-dark and bright bands of decreasing intensity

Wide, and is flanked by alternate dark and bright bands of decreasing intensity

Solution:

We know that the width of the central diffraction maximum is inversely proportional to the width of the slit. If we increase the width size, a, the angle θ at which the intensity first becomes zero decreases, resulting in a narrower central band. And if we make the slit width smaller, the angle θ increases, giving a wider central band. Hence option A is well suited to it.