How to calculate the magnetic field generated by accelerating charges?

In summary, the conversation discusses the use of Jefimenko's equations and the quasistatic approximation in calculating the scalar and vector potentials for electric and magnetic fields. The main challenge lies in solving for the retarded time, which is necessary for the changes in the electromagnetic field to propagate from the charge to the observation point. Resources such as Griffiths and Heald and Marion provide further information and problem sets on this topic.
  • #1
the_m-theorist
31
2
my guess was Jefimenko's equations could be used, am i right? also are there any other relevant equations or methods? also what does the current density derivative in the equation (in terms of the acceleration) for the magnetic field physically mean? p.s. my first post on the internet!
 
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  • #3
You just use the Lienard-Wiechert potentials to get the scalar potential ##\varphi## and vector potential ##\vec{A}## and use the definitions ##\vec{E} = -\vec{\nabla}\varphi - \partial_t \vec{A}## and ##\vec{B} = \vec{\nabla}\times \vec{A}##. The only hard part (and it is a really hard part) in the calculation is solving for the retarded time ##t_r## in terms of the actual time ##t## since the changes in the electromagnetic field carried by the particle have to propagate from the field point of the charge (with which ##t_r## is associated) to the observation point (with which ##t## is associated). See Griffiths chapters 10 and 11 for problem sets on this as well as on the ultra-important application to radiation fields.

EDIT: and also Heald and Marion chapters 8 and 9.
 
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FAQ: How to calculate the magnetic field generated by accelerating charges?

What is the formula for calculating the magnetic field generated by accelerating charges?

The formula is given by B = (μ0/4π) * (q*a)/r^2, where B is the magnetic field, μ0 is the permeability of free space, q is the charge of the accelerating particle, a is the acceleration, and r is the distance from the particle to the point where the magnetic field is being calculated.

What is the direction of the magnetic field generated by accelerating charges?

The direction of the magnetic field is perpendicular to both the direction of the acceleration and the direction from the particle to the point where the field is being calculated. This is known as the "right-hand rule."

How does the magnetic field change with distance from the accelerating charge?

The magnetic field decreases with the square of the distance from the accelerating charge. This means that as the distance increases, the strength of the field decreases rapidly.

Can the magnetic field of an accelerating charge be shielded or cancelled out?

No, unlike electric fields, magnetic fields cannot be shielded or cancelled out by any known material. They can only be redirected or manipulated using magnetic materials or electric currents.

Are there any real-world applications of calculating the magnetic field generated by accelerating charges?

Yes, this calculation is important in understanding and designing devices such as particle accelerators, magnetic resonance imaging (MRI) machines, and cathode ray tubes (CRTs) used in televisions and computer monitors.

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