What actually causes the light wave to bend its path when it goes from one medium to another?

It is a direct result of a wonders called refraction. At the point when a light pillar makes a trip starting with one medium then onto the next, at that point it's speed declines or increments relying on the optical thickness of the other medium. See the word bar here. A shaft is an accumulation of many light beams. All light beams in a shaft move exclusively. In actuality we just have a tight light emission, a beam of light is a romanticizing.