Polarization and diffraction

Light is incident normally on a diffraction grating through which the first order diffraction is seen at 32^@ . The second order diffraction will be seen at

Fresnal Diffraction

Conditions of diffraction is

Condition for diffraction is

The main condition for diffraction to be observed is

Among reflection, refraction, diffraction, interference and polarization, which is the sole characteristic of transverse waves ?

Introduction to Diffraction | Single Slit Diffraction | Diffraction through Circular Pin Hole