Is light faster in vacuum than it does in water?

[DeepGround]

Correct me if I am wrong but light always travels at the same speed, it just takes longer to travel through a body of water because it is not traveling along a straight path as it would in a vac...

 

[Integral]

I've only got high school physics at the moment, so bare with me.


I'm confused? If you timed 2 beams of light traveling the same distance, yet one was in a vacuum, the other say something very dense, like a diamond. Which would reach the end first? The one in the denser medium is slower than in the vacuum yes? Or does time slow down somewhere :D ??

the beam through the denser medium arrives later. Using a laser beam this is effect observed as an interference pattern which occurs if the beams are recombined. The term to research would be OPTICAL PATH LENGTH.

 

[Joza]

Does that mean that the speed of light is NOT a constant?

Yet as I understand it is, always being 3 by 10^8 ms^-1.

Anyone care to explain this?

 

[Gokul43201]

Please read the FAQ - https://www.physicsforums.com/showpost.php?p=899393&postcount=4

 

[Integral]

I am not happy with this ancient thread being resurected, then getting replys by people who obviouly have not read it.

LOCKED !