Diffraction: Bending of waves around obstacles

Steps:

• Recall diffraction definition: spreading or bending of waves when encountering an edge or aperture.
• Evaluate each option for wave bending around an obstacle.
• Identify scenarios involving edges or barriers that cause wave spreading.
• Select the option matching diffraction without other dominant effects like reflection or refraction.

Why C is correct:

• Microwaves passing the edge of a metal plate bend around the plate, exemplifying diffraction as waves encounter an obstacle edge (per Huygens' principle).

Why the others are wrong:

• A: Laser light in optic fibre undergoes total internal reflection, not diffraction.
• B: Light forming images on a screen involves refraction and focusing, not wave bending around edges.
• D: Sound waves diverging in air is due to spreading from a point source, not diffraction around an obstacle.

Final answer: C