• Huygens’ principle
• Diffraction and Reflection
• Refraction

Huygens’ Principle

Given that waves are caused by a source of disturbance, and that waves themselves cause disturbance as they propagate, Christiaan Huygens (1629-1695) treated waves along the principle that:

Every point on a wave may be considered as a point source disturbance, causing secondary waves that spread out evenly in all directions with a speed equal to the speed of propagation of the wave.

Diffraction and Reflection

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Refraction