In the case of single-slit diffraction, the effect of increasing the wavelength is an increase in the diffraction pattern's spread or broader fringes.
Single-slit diffraction occurs when light passes through a narrow slit and spreads out, creating an interference pattern on a screen located behind the slit. The width of the slit and the wavelength of the light are essential factors that influence the diffraction pattern.
When the wavelength of light increases, the central maximum of the diffraction pattern remains relatively unaffected. However, the secondary maxima on either side of the central maximum become more spread out or wider. This means that the bright fringes on the screen become broader as the wavelength increases.
This effect can be explained by the relationship between the width of the central maximum and the width of the secondary maxima. The width of the central maximum is primarily determined by the slit's width, while the width of the secondary maxima is dependent on the wavelength of light. As the wavelength increases, the secondary maxima become wider due to the increased bending of light around the edges of the slit.
In summary, the increase in wavelength in single-slit diffraction leads to a broader spreading of the diffraction pattern or wider fringes.