-1
$\begingroup$

$B= (\mu/4× \pi) × q v (\sin\theta/r^2)$

  • $ \mu = \text{ permeability of medium}$
  • $q = \text{charge of the object} $
  • $r = \text{distance object}$
  • $v = \text{ the velocity of object}$
  • $\theta$ = angle between velocity's direction and r's(distance of charge) direction

This equation needs a velocity of moving charge to tell how much magnetic field it is producing

But All velocities are relative. For example if i travel at 2 lakh km/sec from you then, you will be moving with the same velocity away from me in my view.

If the velocity changes as frame changes how can we decide the amount of energy(in magnetic fields) being released by a charge

how can we say what is the amount of magnetic field released by charge particle?

Improve this question
$\endgroup$

2 Answers 2

Reset to default
1
$\begingroup$

Amount of energy associated with EM field depends on frame of reference. Also, when the charge is moving with constant velocity, no energy is being "released". Kinetic energy of the charge is constant and magnetic energy in space around the charge is also constant. These constants depend on the frame of reference.

Improve this answer
$\endgroup$
12
  • 1
    $\begingroup$ The charge that is releasing the magnetic field doesn't know about other charges around it so it cannot give off magnetic fields according to the charge moving around it $\endgroup$
    – Spidy
    Commented Oct 8, 2021 at 14:04
  • 1
    $\begingroup$ I don't understand your setup. Do you have two charges there? $\endgroup$
    – Ján Lalinský
    Commented Oct 8, 2021 at 14:05
  • 1
    $\begingroup$ Does more powerfulagnetic fields contain more energy? If yes then how will you calculate the actuall strength of Magnetic field since the velocity is not fixed as it changes with frames $\endgroup$
    – Spidy
    Commented Oct 8, 2021 at 14:07
  • 1
    $\begingroup$ Magnetic field has no "actual strength". Its strength at any point depends on the frame of reference. The same point can have strength 1 Tesla in one frame and 2 Tesla in other frame. $\endgroup$
    – Ján Lalinský
    Commented Oct 8, 2021 at 14:09
  • 1
    $\begingroup$ Why do you think source charge gives energy to test charges? It does not. Magnetic force on both test charges is perpendicular to their velocities, so no work is done by magnetic force on these test charges. $\endgroup$
    – Ján Lalinský
    Commented Oct 8, 2021 at 14:17
1
$\begingroup$

No. The magnetic field varies with relative velocity such that the frame-adjusted Lorentz force is the same in every frame. If you like, you can imagine that there is a single "Lorentz Field", of which the electric field and magnetic field are special cases of information normally included as vector components of the Lorentz field.

See this answer for further detail.

Improve this answer
$\endgroup$
2
  • $\begingroup$ What actually happens when a Force is applied on a mass for a time period? Yes! Change in momentum and this tells us that work is being done. In the Case of Magnetic forces work is done by Electric field is created by Magnetic field to apply force on charge $q1$ . $q1$ has got some energy but from where? Less specific answer: From source charge $Q$. More specific answer: From Magnetic field released by $Q$ . Since there is no contact between $Q$ and $q1$ Magnetic fields is more specific answer to say. then $M.F.$ must contain energy. Lets discuss upto this $\endgroup$
    – Spidy
    Commented Oct 8, 2021 at 14:51
  • 1
    $\begingroup$ $g I don't have any problem i finding a way to calculate that force but i am here for an explanation for how this electromagnetism works. We could make assumption but it must explain everything $\endgroup$
    – Spidy
    Commented Oct 8, 2021 at 14:55

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.