Recent content by doaaron

Yes, I managed to reach the same conclusion.This is how I understood Purcell's derivation of the magnetic force for any who are interested. Assume you have a wire with electrons moving at v0 and protons at rest, and a test charge moving parallel to the wire moving at v1. His method to calculate...

I see. Thanks for the tips. I was missing the fact that the transverse momentum in the particles rest frame is minimum. I can see from the equations that it is true, but intuitively, not yet...thanks, Aaron

Hi Jartsa,I'm sorry, but your explanation is very difficult to follow... If the charges move closer, then the charge density is higher. Shouldn't this result in a larger E-field? Why weaker? I don't understand why the charges move closer to the accelerometer in its frame. I thought it is...

Hi Nugatory,that's a good point. Actually that is kind of why I was originally interested to know whether the fact that light travels at "c" for a moving receiver has been proven experimentally. With emphasis on, "propagates at the same speed relative to all inertial observers and without a...

Yup, I'm aware of how it came about...As I understand it, the results of the Michelson Morley experiment could also be explained by an ether drag, and this was the explanation which Michelson (or Morley?) actually believed, but has since been disproven. Also, light not requiring a medium in...

Yeah, I understand that, but I'm just saying that at the time SR was proposed, the experimental evidence was all based on light (to my limited knowledge). So to make a general statement about the universe based on only one of the forces was quite optimistic...Aaron

Hi all,thanks for the help, I think I understand all the points (at least the gist). That's not to say that I am not still a little perplexed... This is one thing that I am still very disturbed by. All the experiments which led to Einstein's theory seem to have been done on light. SR however...

Hi DaleSpam,thanks for the reply. In what way do you think I am attributing velocity to the E-field? My understanding is quite simple: if a charged object is considered to be moving in the frame of reference, then the E-field which it creates will be larger than if it were at rest. This E-field...

I thought that for light, the speed would be independent of the reference frame...I didn't bother with the actual measurements of time and distance for the light case, as it would over complicate things. regards, Aaron

Hi PeroK,the whole point of this thread is to understand the difference in propagation between light and sound (for me anyway). Assume I am an observer in the rest frame and I measure the speed of light from a moving source. I would record the value as 3e8 m/s assuming the medium is a vacuum...

Hi all, OK. I guess I understand. For sound, however, since it travels nowhere near the speed of light, the speed of the receiver relative to the medium has a direct effect on the measured speed of sound. The light experiment in a vacuum is unique in that the wave cannot travel any faster...

Hi wabbit, I meant that for a given medium, the speed of light is constant. i.e. Once you chose a medium, the speed of light within that medium is independent of the speed of the receiver. You thought experiment only proves that the speed of light is dependent on the medium which is...

Hi russ_watters, I intended for the receiver to be the frame of reference since it is the one which takes the measurement. Perhaps this was misunderstood by harrylin in my previous thread. Anyway you also seem to agree with my intuition, so I am still curious if it has been experimentally...

Hi all,I have been struggling mightily through Purcell's book on Electricity and Magnetism, but chapter 5, which deals with the SR explanation of magnetism has me somewhat confused. Suppose we take the following scenario: In the Lab frame, F, electron 2 (e2) is moving towards the right...

Hi all,thanks for the replies. Sorry I didn't make my question clear. I understand that the speed of sound is independent of the speed of the source. In my example, the source and the receiver are the same, however, I am more interested to know if the speed of sound is dependent on the speed...