Speed of Electric Field: Is it the Speed of Light?

In summary, the conversation discusses the speed of electric fields and whether they travel at the speed of light. While some argue that fields are not physical and are just present, it is more accurate to say that changes in a field propagate at a certain speed. In the case of electric and magnetic fields in a vacuum, that speed is c. The confusion around this topic is due to the use of retarded times, but ultimately it is the movement of charges that causes changes in the field to propagate at the speed of light.
  • #1
BeauGeste
49
0
"speed of field"?

Is it correct to say that a field (i.e. electric) travels at the speed of light?
We've been taught that only electromagnetic radiation in a vacuum travels so can we say that the effect of E travels at c also?
I always thought this to be the case but someone argued that fields are not physical and are 'just there'. Can anyone elaborate please?
 
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  • #2
It is better to say that changes in a field propagate at some speed. For electric and magnetic fields in a vacuum, that speed is c.
 
  • #3
ok that makes sense now.
I was a little confused because when using retarded times, it appears that the potential or field 'influences' at c but it's really because when using retarded times, a charge is moving and therefore the field is changing (and the change propagates at c).
thanks.
 

FAQ: Speed of Electric Field: Is it the Speed of Light?

What is the speed of electric field?

The speed of electric field is the rate at which an electric field propagates through space. It is a fundamental property of electric fields and is a key concept in understanding electromagnetism.

Is the speed of electric field the same as the speed of light?

Yes, the speed of electric field is equal to the speed of light. This is because light is an electromagnetic wave, and electric fields are one of the components of an electromagnetic wave. Both travel at the speed of light in a vacuum, which is approximately 299,792,458 meters per second.

Why is the speed of electric field important?

The speed of electric field is important because it is a fundamental constant that governs the behavior of electromagnetic waves. It is also crucial in understanding the behavior of electricity and magnetism, and is used in many practical applications such as telecommunications and electronics.

Can the speed of electric field be faster or slower than the speed of light?

No, the speed of electric field is always equal to the speed of light. This is a fundamental law of physics known as the Maxwell's equations, which describe the behavior of electromagnetic waves. Therefore, it is impossible for the speed of electric field to be faster or slower than the speed of light.

Does the speed of electric field change in different mediums?

Yes, the speed of electric field can change in different mediums. In a vacuum, it travels at the speed of light. However, in other materials such as air, water, or glass, the speed of electric field can be slower than the speed of light due to interactions with the molecules in the medium. This is known as the refractive index and is a key concept in optics.

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