Assertion (A): Diffraction is a sure indication of wave nature.
Reason (R): Only transverse waves can be diffracted.
Diffraction, the bending of waves around obstacles, is a hallmark of wave phenomena, so (A) is true. However, both transverse waves (like light) and longitudinal waves (like sound) can be diffracted, making (R) false.
Assertion (A): We cannot get diffraction pattern from a wide slit illuminated by monochromatic light.
Reason (R): In diffraction pattern, all the bright bands are not of the same intensity.
A diffraction pattern always exists, but for a very wide slit compared to wavelength, it's very narrow and practically unobservable, making (A) practically true. In single-slit diffraction, the central maximum is brightest, and other maxima are less intense, so (R) is true. (R) does not explain (A).
Assertion (A): Diffraction of light is due to dispersion.
Reason (R): Change in path of light around “the corners separates the wavelength of various colours.
Diffraction is the bending of waves around obstacles or through apertures. Dispersion is the phenomenon where a wave's phase velocity depends on its frequency, leading to color separation. These are distinct phenomena. Both assertion and reason are false.