Why light bends when it enters a different medium

[SprucerMoose]

G'day all,

I was just wondering why light bends when it enters a different medium. I understand that the light slows down, but why exactly do all the photons, waves or whatever swing around like a gate? Intiutively, I would assume that they would all just slow down and speed back up once leaving the medium, but not change their direction.

Also this is true for mechanical wave fronts in water. Why when one side of the wave front slows down does the neighbouring side swing around? What tension is holding the wavefront together?

 

[sweet springs]

Hi.

There is no such tension. The front lines of the same phases bend naturally.

Regards.

 

[SprucerMoose]

Why?

 

[sweet springs]

Hi.

http://en.wikipedia.org/wiki/Huygens-Fresnel_principle may help you to investigate the problem.

Regards.