transverse waves spreading out in three dimensions

[Globex]

Transverse waves cause a local motion that is perpendicular to the direction of the wave itself; a transverse wave traveling through a rope must cause the rope to oscillate up and down, side to side, or a combination of the two, a transverse waves traveling through a two dimensional sheet must cause the sheet to oscillate in the third dimension, like in the case of ocean waves. But how do transverse waves spread out in three dimensions (i'm thinking of light in particular). Wouldn't that require a fourth dimension allow for oscillations that are perpendicular to the wave's three dimensional motion?

 

[Mise]

Eh? Perpendicular to the direction of travel means exactly that. Figure out which direction the wave is travelling, pick a direction perpendicular to that. A light wave travelling in 3 dimensional space still follows a straight line, btw.

Waves in an ocean aren't transverse, btw. The water moves in a circular motion near the surface, so it's a combination of transverse and longitudinal.

 

[Globex]

Eh? Perpendicular to the direction of travel means exactly that. Figure out which direction the wave is travelling, pick a direction perpendicular to that. A light wave travelling in 3 dimensional space still follows a straight line, btw.

Waves in an ocean aren't transverse, btw. The water moves in a circular motion near the surface, so it's a combination of transverse and longitudinal.

Then my question is, is light a transverse wave that travels in one direction, or in two directions? I've seen diagrams of Young's double slit experiment where light is represented as a wave spreading out in two directions: http://micro.magnet.fsu.edu/primer/java/interference/doubleslit/doubleslitjavafigure1.jpg, and diagrams where its represented as a wave traveling in one direction: http://nige.files.wordpress.com/2009/05/double-slit-experiment.jpg.

 

[Souron]

I don't get what you see as the disagreement between these two pictures. They are consistant.

A light bulb sends light in 3 dimensions, and it is the 3 dimensional electric and magnetic fields that oscillate. They don't oscillate into another dimension, rather they oscillate in intensity.

 

[Globex]

I don't get what you see as the disagreement between these two pictures. They are consistant.

A light bulb sends light in 3 dimensions, and it is the 3 dimensional electric and magnetic fields that oscillate. They don't oscillate into another dimension, rather they oscillate in intensity.

Ah, that makes a lot of sense. But it makes me raise another question. If both the electric and magnetic fields are oscillating in intensity, and these oscillations are spreading in three dimensions, then what does it mean for the magnetic component of light to always be perpendicular to the electric component of light?

 

[uppi]

Ah, that makes a lot of sense. But it makes me raise another question. If both the electric and magnetic fields are oscillating in intensity, and these oscillations are spreading in three dimensions, then what does it mean for the magnetic component of light to always be perpendicular to the electric component of light?

Exactly what it says: The electric field at any point will have one direction and oscillate in intensity and the magnetic field will have an direction perpendicular to it and oscillate in intensity.

 

[Cardiac Kids]

Exactly what it says: The electric field at any point will have one direction and oscillate in intensity and the magnetic field will have an direction perpendicular to it and oscillate in intensity.

How do you know this ,i don't quite agree this .

 

[peter grimes]

It's one of the fundamental relationships in ElectroMagnetism.