How do water waves and light waves propagate in different directions?

In summary: These laws state that the fields in a given area are not constant, but instead vary with time. This causes the fields to cause fields in other areas, and so on and so forth.
  • #1
chris2112
20
0
I was hoping someone could explain something I'm not quite understanding about light waves. I've researched many sources but I'm still not understanding exactly how they propagate.

light_wave.gif


I understand that the electric field in any perpendicular section of the light ray creates a magnetic field perpendicular to it or vice versa, but I do not understand how they create each other in the direction of the ray to actually create it. I'm hoping someone can help me out with this. Thank you.
 
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  • #2
That is due to Faraday's Law and Maxwell-Ampere's Law in integral form. It follows from those two laws that the fields cannot be confined in free space (unless they interact with matter), and that when you have the fields in a finite volume of space and those fields are time varying then they create fields in every other volume that encloses that first finite volume, so essentially you just can't confined the fields unless you make em interact with matter.
 
  • #3
chris2112 said:
I understand that the electric field in any perpendicular section of the light ray creates a magnetic field perpendicular to it or vice versa, but I do not understand how they create each other in the direction of the ray to actually create it. I'm hoping someone can help me out with this. Thank you.

Think about a more familiar example: a water wave. The water at anyone point only goes up and down in the vertical axis, yet the wave somehow propagates horizontally along the surface. What's going on here is that as gravity pulls the high spot down, the water underneath the high spot has to get out of the way, so is forced sideways causing the water next to the high spot to have to get out of the way... And up is one of the directions that water can move. So the downwards movement of the high spot creates a new high spot adjacent to it.

As Delta2 says, the analogous behavior with electrical and magnetic fields is described by Faraday's and Maxwell's laws.
 

1. How do light waves travel through space?

Light waves travel through space as electromagnetic waves, which means they are a combination of electric and magnetic fields that oscillate perpendicular to each other and to the direction of propagation.

2. What is the speed of light waves?

The speed of light waves in a vacuum is approximately 299,792,458 meters per second, or about 186,282 miles per second.

3. How do light waves interact with matter?

Light waves can interact with matter in a variety of ways, such as being absorbed, reflected, or refracted. The interaction depends on the properties of the matter, such as its composition and surface texture.

4. Why do light waves travel in a straight line?

Light waves travel in a straight line because they follow the path of least resistance, which is the shortest distance between two points. This is known as the principle of least action.

5. Can light waves travel through all materials?

No, light waves cannot travel through all materials. Some materials, such as opaque objects, completely block the transmission of light waves, while others, such as transparent objects, allow light waves to pass through with little or no obstruction.

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