Huygen's principle in practical sense

[americast]

Hello everyone,
I have two little clarifications to make about Huygen's principle: -

• Why doesn't the wave go backward? I mean, if every point on the plane acts as the source of a secondary wavelet, then, along with the envelop which makes the wave travel apparently forward, another should make it travel backward.
• If every point is a source, why doesn't the path of light get illuminated? That is, we know we can see only the source and destination of light, and not its path in between. So, if every point in its path is another source, the entire path should be visible.

Gramercy...

 

[Doc Al]

As far as your first question goes, I wrote something a while back in this thread that might be helpful: https://www.physicsforums.com/threads/huygens-principle-incomplete.236864/#post-1741998

 

[americast]

As far as your first question goes, I wrote something a while back in this thread that might be helpful: https://www.physicsforums.com/threads/huygens-principle-incomplete.236864/#post-1741998

Thanx! Your answer was precise and helpful...Any ideas about the second point...?

Gramercy...

 

[pixel]

Any ideas about the second point...?Gramercy...

Every point on the wave front may be regarded as new sources for the purpose of predicting the future location of the wave. It's not meant to be taken literally.