Consider the central peak in the diffraction envelope in. Suppose the wavelength of the light is changed to 450nm. What happens to this central peak?

If the wavelength of the light is changed to 450nm, the central peak in the diffraction envelope will shift to a different position. The position of the central peak in the diffraction pattern is determined by the wavelength of the light, with shorter wavelengths resulting in a smaller central peak and longer wavelengths resulting in a larger central peak. Therefore, changing the wavelength to 450nm will likely result in a shift in the position of the central peak in the diffraction pattern.

If the wavelength of the light is changed to 450 nm, the central peak in the diffraction envelope will move closer to the center of the screen.

This is because the diffraction angle, which is the angle between the central peak and the first minimum, is inversely proportional to the wavelength of the light. So, when the wavelength is decreased, the diffraction angle decreases, which means that the central peak moves closer to the center of the screen.