what should be the order of size of obstacle/aperture for diffrection of light ?

The order of size is :

Define diffraction. What should be the order of the size of the aperture to observe diffraction.

What should be the order of the size of an obstacle or aperture to produce diffraction of light?

What is the order of size of out galaxy ?

What should be the size of the aperture of the objective of telescope which can just resolve the two stars of angular width of 10^(3) degree by light of wavelength 5000 Å ?

The size of the obstacel in order to observe diffraction fo light must be

The correct order of size is :

The correct order of size would be:

The correct order of the size is