In Fraunhofer diffraction at single slit, if slit width is decreased, the adjacent minima will - 

Concept-

• When themonochromatic light ray fall on single slit then it gets diffracted from the slit and form bright and dark band on the screen.
• The bright pattern is also called maxima and dark band is called minima.
• At maxima the intensity is maximum and at minima the intensity of light is minimum.

The width of the maxima or minima is given by:

\(Sin\theta = \frac{{n\lambda }}{a}\)

Where λ is wavelength of the light, n is integer value, a is slit width and D is distance of screen from the slit.

Explanation-

If slit width is decreased, the adjacent minima will - 

• It gets wider. This is true for single slits, double slits, and diffraction gratings.
• The smaller the object the wave interacts with, the more spread there is in the interference pattern.
• Increasing the size of the opening reduces the spread in the pattern.

So, if slit width is decreased, the adjacent minima will be move apart.