The phase difference of the waves 1 and 2 at A in the given figure is:

A. Focal length B. Flying height C. Ground elevation D. None of these

A. Absorption by the dissolved material B. Absorption by the suspended particulate matter C. Scattering by the suspended particulate matter D. All of these

A. 0.4 - 0.7 μm B. 0.5 mm to 1 μm C. 0.7 - 1.3 μm D. 0.7 to 14 μm

A. $$\frac{\pi }{4}$$ B. $$\frac{\pi }{2}$$ C. $$\pi $$ D. $$\frac{{3\pi }}{2}$$