5 ms·

Wow, this is the first time I have understood why nothing can go faster than the speed of light and why time dilation is a thing. A very easy to read article,

Wow, this is the first time I have understood why nothing can go faster than the speed of light and why time dilation is a thing. A very easy to read article, give it a try. Also if you are curious why a moving charge creates a magnetic field watch this Veritasium video: https://www.youtube.com/watch?v=1TKSfAkWWN0 https://www.youtube.com/watch?v=1TKSfAkWWN0

deleted 5y ago
[deleted]
thriftwy 5y ago
Frankly though, I not sure why they couldn't just use a simpler correction: postulate that moving charge only creates magnetic field with regard to objects moving relative to it. Which is also basically true? This way, the stationary observer will sure notice that there's F_B, but will also know that the charge moving alongside the (also moving) rod does not experience it.
- DangitBobby 5y ago
  That's the thing though, in the article the charged object does not move relative to the rod. The rod, object, and person B are stationary relative to each other. I was actually really surprised to read that two charged objects moving with the same velocity relative to each other generates a magnetic field from A's perspective.
  - whatshisface 5y ago
    Two long charged rods moving with the same velocity relative to each other are two parallel wires carrying current, the second of which is a typical and easy-to-calculate example of electromagnetic attraction. In fact, that situation is so prototypical that it is used to define the Ampere in terms of what current is required to produce a certain force between parallel wires. [0] [0] http://www.physics.louisville.edu/cldavis/phys299/notes/mag_force_2wires.html http://www.physics.louisville.edu/cldavis/phys299/notes/mag_...
    - thriftwy 5y ago
      In this scenario, rods are stationary but they have current running in them - a different situation. Can it be translated to the relativistic one? Maybe what they really wanted to say is "there is a speed c at which the charge of a moving rod is indistinguishable of current running through stationary rod"? Now that would make a lot of sense.
      - whatshisface 5y ago
        It's not different as far as electrodynamics is concerned. The motion of the charge is what matters; whether or not the neutral part is stationary or moving is of no concern.

deleted 5y ago

[deleted]

thriftwy 5y ago

Frankly though, I not sure why they couldn't just use a simpler correction: postulate that moving charge only creates magnetic field with regard to objects moving relative to it. Which is also basically true? This way, the stationary observer will sure notice that there's F_B, but will also know that the charge moving alongside the (also moving) rod does not experience it.

DangitBobby 5y ago
That's the thing though, in the article the charged object does not move relative to the rod. The rod, object, and person B are stationary relative to each other. I was actually really surprised to read that two charged objects moving with the same velocity relative to each other generates a magnetic field from A's perspective.
- whatshisface 5y ago
  Two long charged rods moving with the same velocity relative to each other are two parallel wires carrying current, the second of which is a typical and easy-to-calculate example of electromagnetic attraction. In fact, that situation is so prototypical that it is used to define the Ampere in terms of what current is required to produce a certain force between parallel wires. [0] [0] http://www.physics.louisville.edu/cldavis/phys299/notes/mag_force_2wires.html http://www.physics.louisville.edu/cldavis/phys299/notes/mag_...
  - thriftwy 5y ago
    In this scenario, rods are stationary but they have current running in them - a different situation. Can it be translated to the relativistic one? Maybe what they really wanted to say is "there is a speed c at which the charge of a moving rod is indistinguishable of current running through stationary rod"? Now that would make a lot of sense.
    - whatshisface 5y ago
      It's not different as far as electrodynamics is concerned. The motion of the charge is what matters; whether or not the neutral part is stationary or moving is of no concern.